This question already has an answer here:
I'm replacing the faucet handle (below). But I can't figure out how to remove the stem (in photo above the red outlined area). So I'm thinking I need to remove the stem as well. But I can't see inside to see how to do that.
This other answer explains what the stem is, but not how it connects to the water source, or how to remove/replace it.
I'm also a little worried that if I get it disconnected I won't be able to reconnect it. (Right now the faucet works, it's just hard to close. If I break the stem, I'll have to leave the water off til a plumber visits!)