How to erase the background with the cursor in order to reveal what's underneath?

Hello guys!
I was wondering if any of you know how to make it so when you go over a picture with the cursor it gets erased and what’s underneath shows?
Like this website has it in the beginning when you first open it
Whether its code or anything whatever you think might work pls let me know because I have been trying to figure it our for way too long :))