keep him grouded 在这里是 让某人站稳脚跟,认清现实不狂妄的意思.
译文：但是kieron 说他的朋友让他看清了自己状况；或让看明白了自己处境；让他站稳脚跟认清现实.
参考：
Daniel Radcliffe insists he won’t be getting big-headed like other Hollywood stars — because his family and friends help him keep his feet firmly on the ground.