I'm new to the community, and question, what's a screen wipe?

Might be different depending on the game you're playing, but it's just a type of transition where one image is "wiped" over the other in a specific direction, like a vehicle wiper. It happens in film as well.

Alternatively, the verb "to wipe" may be referring to the death of the player, or the death of all enemies on the screen mentioned ("wiping them off the field").