I just replaced one just like it last fall.
You have a freeze proof Outdoor hose bibb and they are not all created equal when you go and buy a new one.
First they work by having a long tube that goes thru the wall and the actual valve is inside your house where it is warm. They come in different lengths depending on how thick your wall is. They also come in quarter turn and many turn models I strongly recommend the quarter turn version. Inside where the water connects some are threaded and Shark-Bite makes one with the PEX connector on the end if you have PEX plumbing.
There is nothing to fix on them as far as I know if it is leaking get a new one and replace it.
When you install it they recommend it to be slightly down hill so when you shut the water off it can drain out. If you have a hose or a quick connector on there and it freezes out it will still hold water and will break. It is important to always take everything off that’s connected each time if there is a chance of freezing.
You should have a shutoff inside then disconnect it inside remove the two screws outside and pull it thru the wall. It may be stuck as people spray great stuff foam in around the pipe most of the time.