The word mod is short for modified, and a "mod" APK is a version of a software package for Android that has been altered. Because of this, the original developer of the software has not signed the file, and if you download it, you won't be protected by the original developers' support and terms. But the modified version offers extra features, such as unlimited game currencies, extra support, and resources. It may also allow you to access paid versions of a game for free. https://apksunny.com/
If you want to install paid apps, there are several ways to go about it. The first method doesn't require you to download a third-party app installer, and it's simple. If you want to use modded apks repeatedly, you can use third-party apk installers, but beware: these services may contain malware or contain viruses. They're also risky. You'll need to be extra cautious when downloading mod APKs, though, as there are several risks associated with using them.