I need help. I don't know what this means. It's probably really easy so go easy on me.
This probably means that you have already received an error message about the symbol in question - you need to fix that error first, then this one will probably disappear. General Principle: always attend to the first error first! You will often find that one error leads to very many subsequent errors - fix the root cause, and you'll thus fix all the rest at the same time!