In some cases it may be easier to change out the whole faucet. They typically screw on to the copper pipe, but only do so if you can reach the nut behind the spigot so you can put a wrench on it. You can see what I mean here: - YouTube You don’t want to just unscrew the spigot without bracing the pipe since you would run the risk of torquing the pipe.
If you change out the whole spigot, watch a few videos to see the procedure. It’s pretty easy, but you don’t want to skip a step and end up with leaks.
I had a plumber out last year to do some repair work on the shut-off valve to the water supply for one of the toilets. (I was going to replace the flush valve inside the tank, but when I shut the water supply off and tried to drain the tank, I could still hear water running.)
So of course the first thing the plumber asked me to do was to go down to the basement and turn off the main, while he was getting stuff out of the truck. I turned the handle, and it just snapped off in my hand. Water started spewing everywhere, I ran outside to let him know, and he was able to turn off the water at the street. I can only imagine what a disaster it would have been if I didn’t already have a plumber there.
And if you decide to change out the whole faucet, I’d suggest getting a frost-free sillcock, because with those, the stem is long enough that the seat is in the heated part of the house and should not freeze.
Parrot jaw pliers will grip tightly on a round item in a way that other pliers, including vise grips, can’t. If it’s not seized so badly that it absolutely can’t be unscrewed, these will do the job.
Missed the edit: And they don’t have to be squeezed with crushing force to accomplish this. They ingeniously bite into the surface of all but the hardest metal and don’t slip around.
That video makes a point I meant to bring up: When you replace the hose connection, use teflon tape in between the two. In fact, just in general, never screw any plumbing piece onto any other plumbing piece without some teflon tape in between.
It’s like baking without parchment paper, NEVER worth the hassle it causes down the road.
ETA: AFAICT, a pipe wrench has every advantage in gripping a round item that parrot jaw pliers do, and then some - especially being able to throw a pipe around the handle of the pipe wrench to effectively give you a handle a few feet long for greater leverage.
Anyone suggesting vice grips is wrong. They are designed to hold things, not turn things. I have seen too many damaged fasteners and fittings because of them. A pipe wrench and a backing wrench on the faucet should get it off no problem.
Parrot jaw (or parrot nose) pliers resemble curved-jaw water pump pliers, but the curvature is not opposite. Only the upper jaw wraps around the item; the lower jaw is curved (very slightly) in the same orientation. This results in a type of cam action where the biting force into the item is increased by rotation rather than by squeezing.
All of the above plier types have serrated teeth, but that alone doesn’t mean they’ll grip as desired. It’s the particular design of parrot jaw pliers that makes them grip so well.