If it is not an HTML5 app, no.

Thank you for your answer :) But I want to know also if there is an html5 application, does android give me the permission to install it on my firefox OS phone? Thank you again :)

I don't understand the question. Android doesn't have anything to do with FirefoxOS, so it doesn't need to give it permission.

Android applications are packaged in .apk files, similar to how Java turns apps into .jar files. They contain compiled Java code that only runs on Android.

FirefoxOS apps, as far as I know, are packaged in .zip files and is just a bundle of web-files (HTML, CSS, JS) that are unpacked during installation.

Therefore they are not compatible.

However, if the Android app was developed using web technologies and abstraction platforms (like Titanium and PhoneGap), the developer could export the files minus the platform, and with little modification of the API used, could deploy it on FirefoxOS. However, this job is for the developer and not for the client to do.

Some apps are just "thin clients" of their parent website. One could skip the app and just go to their website. Some of these sites are already mobile-ready and are essentially "mirrors" of their mobile apps (like The Verge, Twitter, Facebook).