With traps, creatures, scrolls, and more, various effects might be activated. These effects include remaining, shielding, summoning, and more for x amount of rounds/turns. This timer starts from the end of the turn of the person it was activated on. So if you’re forced by your opponent to remain for 1 round that time will end as soon as their next turn has ended if they activated it on their turn. The effect, however, starts from the moment it was activated.