What is "Mounts Storage" ?

Hi everyone, in instructions to install sweet rom, says "Mounts Storage".
What is this? i flash sometimes and never did it.

And, can replace all this....

,Wipe Data/Cache/Dalvik
,Mounts Storage and Format System AND Format PreLoad

By the options that wipe for install new rom? or i must do like the cooker says??
(yes, yes follow the instructions, but i dont knkow much about "Mounts Storage" jeje

Thanks in advance