According to you Query you are asking about 4x MSAA.It seems that you have access the developer's option in your Android System.It means
4-it is digit
MSAA stands for -Multi-Sample anti aliasing
You have increased 4 times multi sample anti aliasing .
Advantage-In simple if you turn it On your Android system will render games in highest possible quality and give you smooth gaming experience.
Disadvantage- It will drain a lot of battery and your smartphone battery may require charging.
Recommendation-It is recommended that when you have played your game turn off this feature.
By activating Force 4x MSAA setting in Android Developer Options, you can enjoy a better gaming performance. It forces your phone to use 4x multisample anti-aliasing in OpenGL 2.0 games and apps. However, enabling this setting can drain your smartphone’s battery faster.