Quite often while using iOS apps you come across many quirky animations such as an innovative loading symbol, a unique progress bar, a fancier calendar and many more. You may want to integrate all this into your app but have no idea how to build it.
That's where Cocoapods come into the picture. Cocoapods has many libraries, i.e. code written by other people, that are available for everyone to use. You don't have to code all of this from scratch. Just install the library, include it in your code, and you're good to go.
You can also read about Cocoapods more at its official website: CocoaPods.org.
You can search for Cocoapods on the official website. For example, if you want a progress bar for your app, just search for "progress bar", go through a few designs and see what you like best.