What is the main function of color filter in black-and-white photography and color photography?

Do you know the three primary colors of light? Red, green and blue. With ever-changing colors. A green mirror is a thin plastic sheet that filters some light. It is generally used to shoot fashion blockbusters, and ordinary people don't need it.

Buy one and try it yourself. It can be said that 9 and a half people in 10 are not satisfied with the result. Because it is seriously divorced from the lives of ordinary people.