CLEO SA is an app to let you use GTA San Andreas's cheat codes and mods on its Android version. However, you need a rooted device otherwise the app won't work.
Once inside the game, you can activate CLEO SA's menu by tapping your device's button for a couple of seconds or sliding downwards from the upper part of the screen. After doing this, a very intuitive menu will appear where you have to decide which cheat code you want to activate. You can get all the guns, create vehicles, get a jetpack, etc. Basically, you can do whatever you want.
CLEO SA is very interesting app for any GTA San Andreas player, since it can help you to make the most out of your game. But then again, you might miss part of the fun if you start using cheat codes too often.