Protection Zone Block is indicated by the protection zone block icon on your character's status bar. As long as you have the protection zone block, you cannot enter a Protection Zone. While the protection zone block icon is display the Logout Block icon is not displayed.
When you attack other players or set a field rune (fire field, fire wall, etc.), the icon will appear. Players that are attacked can fight back and then run or kill the attacker and not have the block - this only applies to PvP worlds. You will still receive a Logout Block for attacking another player, though.