A setup will allow your guitar to play at a better condition, the string height would be lowered thus allowing you to play more comfortably, intonation would be adjusted. Procedures involved adjusting the truss rod (if necessary), lowering of saddles and adjusting the intonation etc.
There is no recommended interval. Some would say 6 months once and some would do it once a year, it depends on individual and manufacturer and no standard interval. Btw bro, google is your best friend and try searching around on ther forum... All the best!!!