can someone explain common geolocation API error codes?

hey everyone, i'm a total newbie here and just saw the previous discussion about 'why is my IP geolocation tool suddenly failing?' – that post was super helpful for understanding initial issues. but now i'm facing a new problem after trying to fix things. my geolocation API is now returning some specific error codes, and i'm a bit lost on whats going on. it's kinda confusing because before it just failed silently, now i'm getting actual messages. for example, sometimes i get this in my console:

{
  "status": "error",
  "code": 401,
  "message": "Unauthorized: Invalid or missing API key."
}

could someone explain what common geolocation API error codes like this one usually mean? and maybe give me some tips on how to troubleshoot them? i'm really trying to get this working for my small project and any help would be super appreciated. waiting for an expert reply!