The original text is as follows:

A gentleman has three pleasures, and the king of the world does not exist. Parents exist, brothers have no chance, and they are happy; Yang is worthy of the sky, regardless of people, but also happy; It is three pleasures to be educated by talents in the world.

It means:

A gentleman has three kinds of happiness, and being king is not one of them. Parents are alive, brothers are safe and there is no resentment. This is the first kind of happiness; Being worthy of heaven in this life and being worthy of people in the afterlife is the second kind of happiness; Being educated by outstanding talents in the world is the third kind of happiness.

This sentence is relatively simple, expressing Mencius' explanation of happiness in life, that is, the happiness of a gentleman has nothing to do with power, so even if he becomes a king, he is unhappy. Happiness should spread from small to large, from the inside out, not arbitrary.

Parents are alive and brothers are harmonious, which shows that family harmony is the premise of happiness;

Holding one's head high and having a clear conscience shows that a person's attitude towards the world is a necessary condition for happiness;

As for the last sentence, it is actually the greatest happiness for outstanding talents to get further education and promotion, because Mencius is not only a thinker, but also an educator.

Generally speaking, this sentence also conforms to the old saying, "It is better to have fun alone than to have fun with others."

So I guess Mencius should be a very happy person, thinking that happiness should be transmitted and shared, which is why he has such a sentence.

Personal understanding for reference.