This wonderful machine is unfortunately basically useless nowdays. It can oficially only run up to OS X Lion, which released in like...2011, and running newer versions with the help of varoious patchers isn't a great experience either. That being said, I still use it for more niche use cases, such as creating badges for my home page using an ancient version of Photoshop (which I can get for free since it's ancient), or playing older games (like Half Life). You can install Linux on it, and that will allow you to do more useful things like browsing the modern web, but don't expect anything fancier than that.
Funnily enough, running older software (mostly games) works better under macOS, so running macOS on this machine is actually preferable because you get better performance. Which does makes sense considering modern Linux justifiably no longer maintains drivers for hardware from 18 years ago.
Neofetch coming soon.