A music tutor can help you learn a lot about music or a specific instrument far faster than you would be able to teach yourself. Music tutors are qualified people with a trained ear for sound (usually experienced in a range of instruments).
You may want a music tutor to help you learn music theory as well. Many music tutors are able to teach the current curriculum but you should check with them if they are up to date on the latest syllabus.
Lots of people, young and old, find a music tutor to help them play music purely for pleasure. The more tips, techniques and skills you have under you belt for your chosen instrument the more pleasure you will derive from playing.