I need an opinion on internship

I am an mechanical engineering student 3rd year 2sem and we recently got an opportunity of internship for free my college is a tier 2 we don't have many students in class just 3 and the person is in contact with the college I want to ask if I should take the internship now or take in 4th year I have backlog and not very good at studying and how useful is the internship I asked our senior he said it not good he also went to same person