Soffit vents?

They are called metal soffit coverings. They cover your old soffits and some are solid ribbed metal, and some are perforated metal. The perforated metal lets the soffit holes in your eves take in air flow. They are on a rail, and most generally, you can snap them back in place. Is yours damaged? If not, you just need to go back up and snap it back in. If you saw a critter in there, most likely, it has already taken up residence, and you may want to call an exterminator, before it eats your wiring, and anything else it finds up there. The open vents were one time covered with a vent cover, and then someone decided they didnt want to bother with the painting etc, so they covered over it all. I have the same thing here. They do come in different widths, if you need to replace, rather than snap back in.

Thank you cat_ky, that was very helpful !

Funniest post I've read. Thumb's up!