I have to replace this thing that leads to my outside faucet. Looks like it's threaded on.
Any suggestions what to replace it with?
Aby special tools needed?

Looks like a gate valve with a striped stem. Can you get some better photos?

I’m a crawl space veteran.  If you are going to use a torch down there take some wet towels and aluminum foil(to shield the wood).

You also need to tell us if that is a frost free spigot going outside.

I cheated on my last frost free replacement, shark bites and poly to the copper.

I stand corrected, that is above a drop ceiling.  Still, not a hard fix.
Gut it out and replace.

replacing this shut off, might not be the best thing to learn to solder on. especially in that type of location.

id take your phones camera, and or a flashlight and mirror, to see what the valve is. what brand. what size connections. what model #. try to find a packing rebuild kit. or you can most of the time buy the same brand and size valve, complete, and take it apart to rob the guts from it. replace the seal, stem, etc. this might be a poke and hope type of situation.  I did have a 20 year old mueller mixing valve on my boiler 5 years ago not mixing properly. I was able to find the same valve, same size, brand etc, at HD and brought it home, took it apart and put all the guts into the "old" valve body. no problem.

Is this a valve with the handle broken off or is this a flared water fitting like a gas line made to be removed to drain the water out of in the winter? Its hard to tell with half of the subject out of frame.

Turn the water off and unthread that broken handle and take it to home depot or whatever and see if you can just swap out the guts of the valve.

I can’t tell what this is or what it does with the pictures provided.  But I wouldn’t solder it when Sharkbite plumbing fittings are your friend.  Easy to use, easy to remove if you need to, will last, and even code compliant.

Sounds like this is your first rodeo so definitely start here.

thanks folks!