Kiowa admires Jimmy Cross, the first lieutenant and platoon leader, because of how much Jimmy Cross cares for the men in his platoon.
Jimmy sits for hours at the bottom of a foxhole weeping and grieving for the death of one of his men, Ted Lavender. He blames himself for Lavender's death because he was too preoccupied with Martha, the girl he loves, and as a result feels that he didn't do all he could to protect Lavender. It is Jimmy's job, as platoon leader, to protect his men, and he feels that he didn't do his job properly.
As Kiowa looks at Jimmy Cross grieving for Ted Lavender, he sighs and comments admiringly on the depth of Jimmy's sadness. He says to a fellow soldier that Jimmy is a man who really cares. Kiowa himself is unable to feel much grief at all for Lavender's death. He feels guilty about this and wishes that he "could find some great sadness, or even anger." Nonetheless, the emotions don't come, and this is one reason why he admires Jimmy's grief so much. He admires how much Jimmy Cross cares, because he feels guilty himself for not caring.