This command advances your character by one level. Although the level of enemies will respond to this change (they will be higher leveled), none of your skills increase, you do not receive any perk points and also attributes are not advanced.
This is the only way to execute the advlevel cheat - it does not have any arguments. Your character will advance 1 level after executing this command.
AdvancePCLevel is an alias of advlevel - it has the same function.