Passive Mode is a feature in GTA 5 Online multiplayer that prevents other players from being able to harm you with weapons. It also prevents you from using weapons on other players. However, they can still harm you with vehicles and when you enter a vehicle others can shoot and kill you. Passive Mode allows you the chance to evade an encounter with another player(s) that you probably want to get away from.
If you need some time to explore without unnecessary and invasive interruptions, turn on Passive Mode.
When enabled, and on foot, other players can’t shoot you and you can’t shoot them. It’s wildly unrealistic.
Find Passive Mode in the Interaction Menu.
To disable Passive Mode you simply hold your Select(PS3) button or Back(Xbox 360) button to open the Interaction Menu, scroll down to Passive Mode and select it to disable it.