That's a pretty broad era to cover, even for just western Europe, so I'm going to go over some basic bullet points for the evolution of combat in the period. For sake of simplicity, I'm going to use the quick-and-dirty definition of "late medieval" to be around 1300-1500.

1. More field battles and larger armies: Beginning around 1300, the English and the French monarchies began recruiting troops almost entire through contracts. This system never became as big in France, but in England, entire armies would be recruited exclusively through contracts by 1330. This resulted in armies that were quicker to summon and easier to hold together for longer periods in the field. With the ability to maintain armies in the field longer, open battles occurred more frequently, especially in the Hundred Years War. This is all in relative terms, of course. Pitched battles were still not very common in comparison to skirmishes, raids, sieges, and other, less risky, forms of military engagement.

2. Gradual increase in quality and quantity of military equipment: The 1300s saw the development of plate armor come into its own. Shields diminished in size and, for many armored knights, disappeared entirely. That's not to say they vanished from the battlefield, but simply became less relevant for men armored head-to-toe in plate. By the early 1500s, entire armies of pikemen could be outfitted in a basic form of plate with relative ease.

3. Professionalization of military service: While it's a widely repeated myth that medieval armies were composed entirely of peasant levies, armies in the late medieval era were definitely more organized and professional than they had been in years previously. In the 14th century, English armies had relied on a class of non-aristocratic freehold landowners to command and organize bodies of troops raised from the shires. In the 15th century, these men remained officers of archer companies, but even the lower ranks of the common soldiery became more and more professional. Because of the contracts I discussed in point 1, soldiers could expect to be paid in wages, very good wages in most cases. Even for regular foot archers, the daily wage was as good or better than what you might expect to earn as a carpenter in a major city or town. Many of the common soldiers repeatedly signed on for royal campaigns into France and worked as mercenaries in periods of relative peace.

4. Gunpowder: Gunpowder first showed up in on the medieval European battlefield in the mid-14th century, but would not become truly useful until the early 15th. By the early 15th century, cannons had become a necessity for sieges. Cannons were occasionally trotted out in field engagements, but rarely had much effect. That would change in the early 16th century, when artillery finally came into its own on the battlefield as a method of cracking open tight formations of pikemen and halberdiers. Handguns also existed, but were more bark than bite until the 16th century.

So that's some basic characteristics of western European warfare in the period. I hope at least some of that helped you find what you're looking for.

Probably would be better for you to specify a time and place. Late Medieval is a bit subjective and definitely would vary based on where you're talking about, as would the warfare.