If you surf internet with your mobile device often you can have not a very good experience caused by annoying popus and ads.
They requires “Unknown sources” option enabled so you can install the APKs.
ABP and Blockada can even work on non rooted devices.
On rooted devices you just need to install Adblock Plus, open the app and give super user permissions when required.
On non rooted devices follow the instructions for configuring Adblock Plus for Android.
AdAway is an opensource ad blocker and requires root, you can download for free from F-Droid, it uses hosts file to block ads.
Blockada is opensource and has an easy setup, it works with all installed apps, not only the browser!
You can also download browsers that have built in Ad Block feature like Brave Browser.