Display score in 3D widget?

I’m creating a very simple game of throwing balls into a box. I have a widget floating above the box, I want it to count the number of balls in the box (as you score). I’m confused about how to use variables.

I have my 3d widget set up with a text box that is bound to a function. This is where I’m lost (even after scouring through online tutorials :/)

This is my event within the box BP:

I need to now send a signal to my widget BP to check and update the score based on that variable. But have no idea how. Help?