What is the Object in the Cast To node supposed to be?

I am making a light and switch which can be placed around my level independently, the light blueprint should detect if the switch is on and change the material of the light mesh (between emissive and non-emissive material for the light) accordingly. To do that i need to access a boolean in the light switch bp which i would cast to, but i can’t for the life of me figure out what goes into the Object pin, any help is much appreciated!