Assuming from his very vague question that he is talking about the in-game ranks of the game...
Improvements in a player’s general and class-specific skill level are rewarded periodically with promotion to a superior rank. Ranks in Enemy Territory range from Private to General. To obtain a higher rank you have to gain XP in 3 general groups explained below being... light weapons, battle awareness, and one that is class specific. Ranks are displayed on the player’s helmet for everyone to see as well as the bottom left of your hud.
Light weapons - gain xp by killing with any smg (ex. thompson, mp40, sten, fg42(unscoped), sniper(unscoped), ect.)
Battle Awareness - gain xp by surviving for certain lengths of time while giving and receiving damage
Class Specific - gain xp by doing certain class specific tasks for example if you are medic by reviving teammates and handing out health boxes.
When you have received enough xp you will be rewarded a new level symbolized by a star,again displayed in the columns at the bottom left of your hud, thus improving your rank. To check how much xp is needed for the new level press by default the "Alt" button. All 3 groups have 4 levels. Every new level will add improvements such as increased ammo, increased health, and faster reload for example.
hopefully that makes some sense and ultimately was actually what you were asking about.