There is a hole in the side of my furnace

There is this hike that lets out a lot of heat in basement front the side of my furnace. Looks like the metal cover fell over or is this supposed to be open. Someone please tell me

source https://hvac-talk.com/vbb/threads/2244067-There-is-a-hole-in-the-side-of-my-furnace?goto=newpost