Use a property from another blueprint

Hello, I’m trying to make a ball moving in the direction the player is facing when he press a button, so I want to apply an impulse on the ball using a vector that correspond to the direction that the player is facing. I was thinking about using a “get forward vector” but then I need to get this value in the blueprint of the player and transfer it to the blueprint of the ball and… I can’t find how to do it.
I searched, I tried to use a global variable but I can’t find it on the blueprint on the ball, I also saw that it can be done with the us of a blueprint interface but I really don’t understand how it works.
So I was wondering if anyone could be nice enough to explain me how to do it.