Not sure what these are called or what they are for but we had a freeze a couple years ago and every time now I hook up the hose, water shoots out everywhere. I tried to remove it with no luck. I didn't want to force it and damage something so I figure I would ask the experts. How can I fix or replace this?
The big round thingy under the handle is a vacuum breaker. It is to prevent water in hose from being sucked into the house water.
Can replace it just by unscrewing and replace with a new one.
1The thing to know is they usually have a set screw that’s tightened to the point where the head breaks off, so you’ll probably need to use a lot of force. (A big pipe wrench would help.) Dec 18, 2022 at 20:48
They are sometimes affixed permanently by being crimped onto the spigot outlet (which would require replacement of the whole fixture). If you don't see a set-screw, be careful because you could break the pipe it's attached to. Dec 19, 2022 at 0:17
It is called "backflow preventer"
It is just screwed on, you might need pliers to remove the old, then replace with new one.
They function is to prevent water back flow.
Important: Check if it has a small screw on the side, which is there to prevent it from becoming loose. As seen on the picture