In other words, "most OF people" is incorrect English (you need to add "the")

Most people refers to the majority of people/people in general while most of the people refers to a specific/known group of people. Examples: Most people found the movie enjoyable. Most of the people I know don’t like watching movies.

You use "most people" when referring to an indefinite group of people, and most of the people when referring to a specific group of people.

Hi Helen! When you say most people, it means you're talking about the majority of people and when you say most of "the" people, you're talking about an specific group.

You're welcome!