Damn it, I’m trying to convince the wife that we shouldn’t get a second dog, and then you post pictures of a puppy! It’s a conspiracy! Absolutely cracking spaniel that!
My tip, as people have already mentioned, would be to socialise her as much as possible. People, dogs, cats, cars, bikes, postmen, get her used to be around everybody and everything!! Our collie was 15 months when we rescued him, he’d never been socialised, and we’re still having trouble with him being overprotective etc 3 years later. He’s improving, but if he’d been socialised as a puppy we wouldn’t have anywhere near as many issues with him barking/going absolutely mental at things.
Good luck!