If you walked 10 miles around a lap how many times do you have to go around?

If you mean how long does it talk to walk 10 miles then it depends how fast you walk.

Taking 2.5mph as quite leisurely and 5mph as very brisk then walking 10 miles will take 2 to 4 hours.

5mph is very brisk even on road, 3 to 4mph is good pace for off road and/or hilly terrain.