This option allows you to improve the graphics quality in OpenGL ES 2.0 games and applications. Of course, this will demand more hardware performance and consume more battery power. However, in some games and applications it will improve the image by smoothing the pixels. MSAA 4X stands for Multi Sample Anti-Aliasing 4x.

Multi Sample Anti-Aliasing 4x or MSAA 4x allows you to improve the quality of graphics in OpenGL 2.0 games and applications this option will demand more hardware performance and consume battery power faster but will improve the image by smoothing pixels

It means, to force a smoother edges and not to notice the sawtooth (the detonation of pixels that look like stairs or saw on the edges), ie that the edge of things look flatter and if you force it will spend more battery and heat more your celu (in case of low or medium gamma celu not try).

If you force the MSAA to 4x, the edges of things inside any video game will look smoother, but your performance may drop. I recommend using it on high-end mobiles or even some mid-range ones.

Simply put, it will look better but run slower.