Your account will be locked. Nobody will be able to log in and access any of the account's functions. Administrative action will be required to unlock it. You should contact an admin after this (see the sticky in Meta). Be warned that although it will be easier to recover an account after this locking tool is used than if you do nothing and your account is compromised, our account-recovery throughput is very limited, and it could be a long time before you get your account back.