Firefox is a browser, which is what you use to go on the internet. If you have a Windows PC you probably use Internet Explorer or its new version, Edge. Chrome is another browser, made by Google.
If you want, you can download and install Firefox for free here: https://www.mozilla.org/en-US/firefox/new/ . It does not remove or replace your current browser, just gives you another option. Once installed, you can add apps (like on your phone) and one of those is Adblock Plus. If you download that one it should take care of most ads/pop-ups. Let me know if you (or anyone else here) need some help with this.
Importing settings and passwords from another browser saves you the trouble of having to do that manually.