0 - "off". Everything is off, the key is removed. When the key is removed, the mechanism of the mechanical anti-theft device is activated, which affects the steering shaft. To lock the steering shaft, turn the steering wheel to the right or left until it clicks. To turn off the anti-theft device, insert the key into the ignition switch and, slightly turning the steering wheel to the right and left, move the key to position I.
I - "ignition". The ignition is on, the key cannot be removed.
II - "starter". The starter is on, the key cannot be removed. The key position is not fixed: when the load is removed, the key returns to position I.
The ignition switch has a lock that prevents the starter from being engaged when the engine is running. To restart the engine after an unsuccessful attempt, turn the key from position I to position 0 and then engage the starter again.
[The text is copied from the online portal VAZbook.ru]
In variant designs of ignition switches, the angle of rotation of the key from position "0" (parking) to position II (starter) can be 900 or 1350.
To avoid discharging the battery, do not leave the key in the ignition switch!