How do I get the normal of a slanting object?

How does one try and make it so when a player is climbing, the game checks the angle or normal of the surface, and then applies the correct mechanism? There used to be AngleBetweenVecs, CrossVecs, etc, but they got taken out when Blender was transitioning to 2.5 years ago, and since then, I have found no identical built in function. An example is when the player deflects off a wall.

simply by using .angle()

vec1.angle(vec2)