Hi sarmadali123
root means gaining full access to your mobile. It means that you make yourself an administrator. Like that you can use apps that you normally could not use and get the full potential out of your phone. Cyanogenmod is a customised firmware ( such as android) but with more options. I rooted my phone when I first got it and its the best way to properly use your phone. Be aware that Samsung officially announced the update to either ics or jb which should be coming this month ( hopefully). I made a own youtube channel about all cool things you can do with the BEAM (for example play angrybirds with a bluetooth keyboard), please have a look you wont regret
. Just type in allabouthegalaxybeam in youtube and you find my channel. On Feeds I put a link were you can get the information how to ROOT your device. I suggest you take a look. Good luck!