There is a hole field of coin study. Many people research and collect them, and, as a result, there's tons of information available online about it. Real is just one part of a series of coins and measures within the Spanish coin system. Remember, this system, like many out there at the time, were not based on the same kind of basic system of "100 pennies go into a dollar, and then everything else is measured in dollars" or something like that.

32 reals went into a doubloon (also known as a pistole). If you're wondering where "Spanish dollars" and "pieces of eight" work into this, a piece of eight is worth 8 real.

Other coins in the Spanish system during the Golden Age of Piracy that all fall in value behind the Real is Octavo, Quarta, and Marvedis.

If you're wondering what any of this is worth - there is no use trying to crunch this into a modern value, too much changes over time to provide that with a meaningful value.
But, here is context. An English sailor made roughly between 1 and 2 pounds sterling a month during this time. There are 20 shillings to a pound sterling, and 12 pence to the shilling. A Spanish real, according to the 1728 Cyclopaedia is worth 6 and 3/4 pence, a piece of eight worth 4 shillings and 6 pence, and a doubloon (or pistole) worth 17 shillings and 6 pence.

Anything in addition to that, I would recommend digging into the information the coin collectors provide.