While there's a lot more to being capable of taking pictures "like Professionals" than knowing how your camera works, it's certainly a good starting point. If you didn't get a manual with the camera you can
download one here.
After you've got all that worked out (until you can do it all in the dark)..... that's when learning about photography begins..... Composition, Lighting, etc. For that, it takes quite a bit of study and more practice - reading books, visiting galleries, viewing lots of pictures at sites like Flickr .... which even has a
Nikon L120 Group. Follow the discussions there, ask questions, learn from the photographs.
You may be told that the L120 "isn't a professional camera". Some truth in this, but it depends how it's used.... I bet you could still take competition-winning pictures with it, regardless of the specifications. There's a reasonable
review and conclusion about the L120 here..... it has its limitations and is probably a better camera for video than stills(!) - but the pictures on Flickr tell me it's very capable, when used within its constraints.