A "great tutor" refers to someone who is very skilled and helpful in teaching and guiding students. They have the ability to explain things clearly, understand the needs of their students, and inspire them to learn and succeed. Full definition
When I ran the Chicago public schools, I almost had to sue our Department of Education here for the right to tutor our children after school, the kinds of great tutoring programs that everyone, you know, everyone here in this room was involved in. (npr.org)
I think that Mack is a great tutor to the other Oline guys and he might be able to help him find his way but you just invite him to camp and let him compete. (sbnation.com)
My old pal @KevanJonesMPan astute, formidable & experienced voice on Defence - and a great tutor when I was Labour's Defence adviser. (politicshome.com)