The equator gets the most sun and has the warmest climate. This has to do with the tilt of the Earth on it’s axis. As you go north or south from the equator toward the poles the Earth’s temperature gets colder. It is harder for the sun’s direct rays & the curvature of the Earth to reach these points This has to do with the direct sunlight that reaches the equator. Think of a ball, or take a flashlight & shine it on a ball to see this yourself from different angles. The angle of the sun on the the Earth also causes different seasons.
