help new to this app

What is your average cycle length what does that mean I'm new to this pls helpπŸ€”πŸ€”πŸ€”πŸ€”πŸ€”πŸ€”πŸ€”πŸ€”πŸ€”πŸ€”πŸ€”πŸ€”πŸ€”πŸ€”πŸ€”πŸ€”πŸ€”πŸ€”πŸ€”πŸ€”πŸ€”πŸ€”πŸ€”πŸ€”πŸ€”πŸ€”πŸ€”πŸ€”πŸ€”πŸ€”πŸ€”πŸ€”πŸ€”trying to keep track of my period pls help me