A redirect is a way to send both users and search engines to a different URL from the one they originally requested. The three most commonly used redirects are 301, 302, and Meta Refresh.
To understand all the concepts, I advise you to refer to the Moz article. It's helpful and also written in easy language. The author has illustrated all the things in detail with media files & examples.
For the detailed information: https://moz.com/learn/seo/redirection
