Collision info is contained in a KinematicCollision object.
How you access this, depends on how you're moving your KinematicBody.
1) If using
move_and_collide(), it's the returned value of the function:
var collision = move_and_collide(velocity * delta)
2) If using
move_and_slide(), you can get collision data with
get_slide_collision(). However, you have to keep in mind that when using this method, it's possible to have multiple collisions in a single frame (when you move into a corner, for example):
velocity = move_and_slide(velocity, Vector3.UP)
for index in get_slide_count():
var collision = get_slide_collision(index)
Please see the KinematicBody reference for details.