How do I add knockback to the player when he gets hit in a 2d platformer

I making a 2d action platforming game but it just doesn't feel right yet. Whenever the player gets hit by an enemy he just stays there and gets pushed back slowly only because the enemy is a solid. I want to know how to add knockback whenever the player gets hit.

There's vector on the platform behaviour that moves an object like a push or jump depending on x or y.