Energy from the sun can make electricity which can be stored in a battery. Blowing wind can turn turbines to generate electricity. Falling water, which makes hydroelectric power, can also drive turbines.
Geothermal power relies on heat deep in the earth to make steam to drive generators.
In a similar way, nuclear power uses the heat of tiny atoms to create steam. Such energy is called renewable because it generates electricity without using up a resource. It doesn't burn fuel like gas or oil. While gas and oil take millions of years to form and will one day be gone, the wind will always blow. The sun will shine for millions of years and the earth will continue to be hot deep underground.