OLL is the third step of the CFOP method: it makes the whole top face one color with a single algorithm.
There are 57 OLL cases (58 counting the one that is already done). To recognize them, look at the edges first (dot, line, L or cross) and then at the corners. Press a case to see it on the cube.
In the algorithms, Rw is what other sites write as r (two layers) and M is the middle layer.
Cross done (OCLL)
Corners already oriented
T
P
C
W
Square
Lightning
Fish
Knight move
Awkward
Small L
Line
Dot (no edges on top)
Want to really learn them?
In the academy you practice them with hints on the 3D cube, and in the trainer you drill random cases until you know them by heart.