A condition is a continuing problem that a character suffers. A character suffering from a condition has that condition's effects applied at the beginning of their round, unless otherwise stated.
Often, Conditions can be ended with a saving throw. At the end of their turn, a character who is suffering from one or more Conditions can Make a Saving Throw as a free action to end one of these Conditions. The character chooses any one Condition, and rolls the saving throw listed for the Condition against a TN of 12. If successful, the Condition normally ends.
A character can also take a simple action to Shake It Off, which allows them to make an additional saving throw during their turn. If you attempt to Shake It Off, however, you cannot select the same Condition at the end of your turn as you chose when you attempted to Shake It Off.