what is this Multisampling Anti-Aliasing Mode (8xMSAA)

[meow]

does it improve my fps or not

[Caenbet]

Simply put, MSAA just smooths out the edges on textures in the game. It's more resource intensive and won't bring up your fps.

[GunsAhoy]

to add to this
fxaa will perform better
txaa will perform better
msaa and mfaa might be a good option
you can control AA in game or in GPU driver

i would say test all of these out your self