Hav is a Sergeant in Amaram's army. Amaram sends the new recruits to him, including Kaladin and Tien. He seems to have been in charge of the new recruits in the army.
Hav harassed the "lad" (i.e., Shallan in disguise) as s/he began to infiltrate the perimeter of Amaram's manor. He insists that from then on that s/he report at the guard posts when s/he visits and then waves her/him on through.