The peer review process is a part of the research process. Remember! The research process is cyclical.
What does it mean when an article is peer reviewed?
First, scientists do some science.
Then, they write up their findings.
They submit their article to a journal for peer review.
The journal sends the article to other experts in the same field to review before publishing.
If the article stands up to peer review (review by the scientists' peers) it can be published in the journal.
Other researchers can now use that research to do their own research.
And the process begins again.
Remember: not all scholarly resources are peer reviewed!