Extra Turn is a status that lets the user take another turn after their turn ends. The status can stack to give the user multiple extra turns through Fury.
The effect decreases by 1 on the start of the user's next (extra) turn, which starts as soon as the user ends their turn. The turn counter will still increase, meaning that equipment like Polar Star will toggle from being active to inactive.
The gadget Time Stop also grants an extra turn, but it breaks after one use.