DayZ Borealis introduces a sleeping system. This system may remind you of the character system from the game Rust, in which when you exit the game, the player's character remains on the server, and any other player/mob can kill it or pick up/put anything in its inventory.
In DayZ Borealis the system works exactly the same. After exiting the game your character "goes to sleep" and any other player/zombie/mob can kill it, take or put anything in its inventory.
The system also saves all your wounds, the amount of food and water, the amount of blood and HP, etc. Because of this, if for example you log out with an unbandaged wound or with an empty stomach, then your character at some point will die while sleeping from blood loss or starvation.
If your character dies while you are offline, then when you connect to the server, you will re-spawn on the shore. Also, if you don't log back into the server within 7 real days, then your character will die.