What are Java Classes, Methods, Attributes, and Objects? [duplicate]

I'm learning java, and I came across some things like that, actually I'm learning alone on the internet, I just learned to perform the famous "hello world" and found it quite simple, but I read some things and talked things like attributes , methods, classes, objects ... what are they and how do they know how, when and where to use them? if possible, examples of each, thank you !!