Welcome to the forums @BadSadCoder!
What does the code for your enemy look like?
Most times, a bounce or change in direction is generally just flipping the a positive value to a negative. For example:
if (is_moving_left == true):
velocity.x = -MOVE_SPEED * delta
else:
velocity.x = MOVE_SPEED * delta
And then you would just need to change is_moving_left to true/false when the character collides off the wall.
That is just one way to handle it though! There are other ways that might work better depending on your project.