Do you mean the em dash (--)? If so it's used to identify a completely separate section of a sentence that adds some additional information. It's "almost" a replacement for brackets() Ex: I understand your question - about punctuation - and hope that I can help. The section between the em dashes is not required for the sentence to make sense. It adds a bit of extra information, but it could be removed and not change the meaning. Here's an article about the this and the many other ways it can be used: https://www.dictionary.com/e/em-dash/

Do you mean a "dash"? If yes, it is used to emphasize additional information, join independent clauses, mark non-essential information, offset lists placed in a sentence.

Hi Blake, good question. This symbol, (?) Is a called a question mark. You use it when you are asking a question and you write it at the end of that question. For example, "What is your name?"