Can you go to hell if you eat meat on Fridays during Lent?

A sin is committed. It is a seirous (mortal) sin if the person is above the age of 14 and does not have a special dispensation, knows that it was a sin to do so, and ate meat anyways.

It is a venial sin if it was done by accident (but not through carelessness) or without really understanding this. And of course, there is no sin if it was not done with any consent of the will.

In the case of a mortal sin, a confession is needed. In the case of venial sin, a confession is a good idea, but not required. A normal act of contrition and some self-specified penance is needed.