Although she is small in stature, she is very strong.
Tips
usage
个头 is colloquial. For people it means height/build: 个头高/矮 (tall/short stature). For objects like fruit it means size: 个头大/小 (big/small in size). The formal word for height is 身高.
register
个头 is informal and spoken. In writing or formal contexts, use 身材 (figure/build) or 身高 (height) for people.
