In every programming language, you can add in comments with your program. Comments are lines of code that will not be executed with the rest of the program. It is wise to indicate comments because It can help you remember what you're doing yourself if the project is quite big. Also, it can be helpful for others that may see your program. This can help them learn to code themselves.
To enter multiple line comments, or comments that are going to take up more that one line (like a paragraph) you will use the /* and the */ characters.
Now that we've covered that, lets go ahead and move on to Variables and Constants.