The noun people may be used in the plural or in the singular.
The noun people in the meaning of men and women always requires a verb in the plural:
People are walking in the park.
American people are an uneducated.
The noun people in the meaning of a nation has both singular and plural form –
people / peoples.
Long live the friendship of all the peoples of the world!
The peoples of the world are striving the better economic cooperation.
They were such a brave people.
The word folk always takes the verb in the plural