What is it called and how do I replace it? What does it do?  Maybe just take it to an auto parts store?

Warm Air Hose....
https://suzukipartsusa.com/shop/engine/engine-parts/engine-parts-engine-parts/warm-air-hose-suzuki-samurai-86-95-atlga/
Butch

The dimensions on this say 48" and 4x4". Is that a misprint. Mine is 36" by 1 3/4" diameter.

I should have asked you the Car info... My suggestion was for a Samurai... Sorry about that...
Butch

I do have a Samurai, an 87, so I don't understand the discrepancy in the sizes.

The dimensions on this say 48" and 4x4". Is that a misprint. Mine is 36" by 1 3/4" diameter.

You'll need to address that question to the vendor - the description says it fits the Samurai, which appears to be what is in the picture you posted.

Larry... I think that is the same one I bought from them a while back for my '86 Samurai, and it fits fine... I don't have the receipt in front of me, but I believe that that is correct.. Fordem's suggestion is a good one...
Butch