I was curious to know if the indigenous american societies from the North to the South of the western hemisphere had discovered/learned mathematics, up to what advanced degree and finally, how did they employ it in the real world?
Absolutely yes. While there are likely others who can answer this better than I can, (I am not a math expert) perhaps the best example of pre-Columbian mathematical knowledge is the Long Count Calendar, the creation of which required extremely advanced mathematical knowledge - including the concept of zero dating to at least 32 B.C.E. - one of the earliest instances in recorded history.
Notably, the Long Count was not the only Mesoamerican calendar, though it is perhaps the most famous. (It's the one everyone freaked out about in 2012.) There was also a 365-day calendar divided into eighteen months, and a unique 260-day sacred calendar. These two calendars allowed timekeeping to occur in Mesoamerican societies; every day within a fifty-two-year period had a unique identification, then after that point the calendar rolls over. Obviously, this could cause problems, which is what led to the creation of the Long Count. Similar to how B.C. and A.D. are separated by the birth of Christ, the Long Count had a starting point which, in our calendar, is (approximately) equivalent to August 11, 3114 B.C.E. This date, in the Long Count calendar, is designated by 0.0.0.0.0. Because the Long Count would be impossible to have without the concept of zero, and because the earliest date we have evidence of a Long Count date for is 32 B.C.E., the concept of zero in Mesoamerican societies can, at a bare minimum, be traced back to that date (but probably earlier). The use of calendars in general in pre-Columbian Mesoamerica can be traced back to at least 750 B.C.E.
The development of mathematics helped lead to the development of writing, which Mesoamerican societies developed independently (though many of their manuscripts were destroyed by the Spanish - and time - we still have some today).
Even though, of course, indigenous peoples did discover mathematics, it's important to note that just because a society fails to independently invent a certain technology, that does not make it inferior. The Mesoamericans had it especially rough because they had practically no one else to borrow from. While Europe, Africa, the Middle East, India, and China all exchanged developments and technologies with each other for millennia, Mesoamerica was essentially isolated (not totally isolated - there was, of course, trade among indigenous Americans) and had to develop most of what it did independently. But as my source puts it, drawing on another example of missed technology:
"...the Chinese invented the moldboard plow by the third century B.C. Made of cast iron, the plowshare was shaped like a V, with the blade carving into the ground and the two arms arcing away like gull wings. Because the arms were curved, they turned the earth away from the blade, which both reduced friction and more effectively plowed the soil... The design of the moldboard plow is so obvious that it seems incredible that Europeans never thought of it. Until the Chinese-style plow was imported in the seventeenth century, farmers in France, Germany, Italy, the Netherlands, and other states labored to shove what amounted to a narrow slab of metal through the earth... Every society, big or little, misses out on "obvious" technologies."
Source: 1491: New Revelations of the Americas Before Columbus, by Charles C. Mann (I highly encourage you to check this out, he explains math concepts much better than my math-blind self can.)
I would add to the answer already given with some talk of Maya Astronomy.
They were really really good at it.
Some of the calculations the Maya made for the rotations of the planets (namely Venus), were more accurate than those Europeans possessed at the time. Part of it is that the Maya used a base-20 numeral system that was far more manageable than what Europeans were working with prior to the adoption of Arabic numerals. While that might seem like just watching the stars or some such, it meant a lot to the Maya.
The layout of their cities heavily corresponds to celestial movements. E-Groups, an arrangement of structures (usually pyramids) typical of many Maya sites, were functional observatories. While the interest in Venus as the morning and evening star is the most well known, the Maya were aware of Mercury, Mars, Saturn, Jupiter, and the Milky Way. Many major temple sites are oriented to the movements of these bodies.
They'd also calculated Zenith Passage, something that you really only see in the Tropics. It happens twice a year, when the sun passes perfectly overhead and can cast very short or no shadows on vertical objects. The locations of a few temple sites are such that Zenith Passage is fixed to a particular spot or geographic element.
We have no overt evidence of geometry in Mesoamerica, but there is an argument we should infer knowledge of geometry from the ubiquitous presence of several ratios in Maya art and architecture. The Golden Mean (1:1.618) is everywhere in the Maya world, especially in their structures. The square roots of 2, 3, and 5 are also all over Maya art, where the lengths of arms, legs, and the angles of many drawn figures seem to adhere to a strict aesthetic based on these ratios. Christopher Powell has been putting a lot of research into this since he was a grad student (His thesis can be found here, and his dissertation here) and is the main proponent that the Maya had more geometric knowledge than we suspect. I don't think he's written a book on this yet. There are probably some articles on JSTOR.