Shed row - Tradução em português

Richard: Yes, when I was going to high school, I had the opportunity to work at the Lansdowne Racetrack, located in Richmond. What I was classified as was a "hot walker." I would get up every morning about five o'clock and head over to the racetrack, and when I got there, it would be my job to take the horses one at a time and walk them around a shed row for half an hour

What does A SHED ROW mean?
I didn't get the idea of 'Hot walker' either.