Student or Learner
He has a small brain. Is this a correct way to indicate that a person is not very intelligent ? (Maybe there are better ways to express this, but I would like to know if "he has a small brain" is a correct sentence.)
A correct sentence grammatically, but would imply that the brain is physically small.
"He is not very bright" is sometimes used to express lack of intelligence. There are probably other phrases that people can offer you.