are you talking about ACTUAL farming? like growing plants? if so then gtfo.
if you wanna know what fps farming is, its what i stated above. you get 1 or more computers with "cow" accounts (accounts only used for killing)
and you go into a private room and shoot them to your hearts desire.
When You repeatedly kill another player (Bytheir knoewledge) it's "Farming" Because you are synthetically creating Experience Points by Putting in an amount of work. Kind Of How a Farmer, Gains crops rather than having to go to a store to buy rations, By Putting a certain amount of work in.
Or I guess....It Could have a darker meaning....Like When A Farmers Slaughter their animals for meat Ect... xD
It's just an easy way to rank up, Some people create bots to help with this, and many people, even clans are dedicated to "Main" (Farmer) Accounts, Gaining EXP+ On "New" (Cow) Accounts. :P