Heat is a form of energy that flows from one thing to another. The sun's rays are energy that is absorbed by objects that turn this energy into heat. The sun's rays warm darker colored objects more than they warm lighter ones. In the summer we feel hotter when we where black clothing because it is absorbing the heat. But we feel cooler when we wear white because it is reflecting the heat.
Energy has different ways of moving from warmer matter to cooler matter.
Conduction is when a warmer object touches a cooler one. Energy flows from one atom to another in the warm object. These atoms hit the atoms in the cooler object making a cool atom warm. The atoms continue hitting all the cool ones until they are warm. Energy or heat moves easily through some kinds of matter.