How does the rock cycle help us to learn Earth's past?
Some common types of rock are igneous, sedimentary, and metamorphic. I recommend that you get familiar with these terms.
The rock cycle is actually the process by which rock changes shape/form. It often takes hundreds of thousands of years or more to complete just one cycle. For example, of a large amount of igneous rock is found on the Earth's surface near a large mountain, then it is possible that the mountain was once an active volcano.
In this way, based on the type of rock that is present in a particular place (and other factors such as age), geologists are able to learn more about Earth's past.
I hope that helps!