Martin Luther King, Jr. said:
The function of education is to teach one to think intensively and to think critically. Intelligence plus character – that is the goal of true education.
Can anyone tell me in simple terms what he means?
These are two separate quotes from a single address that King delivered at Morehouse College in 1948. In context, the address is a critique of education, particularly education that does not improve people morally or mentally. https://projects.seattletimes.com/mlk/words-education.html
"Thinking intensively" is "intelligence". "Thinking critically", which here seems to mean assessing what you are told against a moral standard, is "character." So the two sentences say the same thing, but in different words, and in a different order.
Together, they express King's belief that the goal of education is not the simple gain or memorization of knowledge, but rather the ability to think and judge.