what's this and what's it for?
I was cleaning the engine and the hose broke off.
it looks like its clogged up.

 

It runs coolant to the thermowax for cold starts. I've seen them corrode, but not that badly. Don't start the car with it off or you will have coolant all over. The piece comes off the BAC by way of the 2 screws.

You can bypass it until you source another one.

 

ok thanks

 

That is the BAC valve, for idle control by the ECU. You can jumper the hose to the other end with a hose adapter from the local auto parts store.

You can replace just part that the hose goes in and out of (that corroded metal section is only help onto the BAC with two small screws).