Firefox for Android, Firefox for iOS (for iPhone/iPad), and for desktop (Windows, macOS, Linux) is a web browser. The company Mozilla does not have a search engine of their own. A search engine service for example is duckduckgo.com, google.com, bing.com etc. You can change what search engine you want to use in Firefox for Android. https://support.mozilla.org/en-US/kb/manage-my-default-search-engines-firefox-android