I've sat in row K in this section once; for a Blue Jays game. One of the best field box sections and one of the best sections in the entire ballpark. Seats and rows are a little intimate and crammed. But you will enjoy being able to see the game this close. Rows here are A thru M. There are also two rows at the foot of the section, those are rows 1 and 2.
Best thing about Fenway Park is pretty much everything happens on one level. No excessive climbs to seats. The best baseball atmosphere or all 30 MLB ballparks.