To exert a permanent, you choose to have it not untap during your next untap step.
July 3, 2020 · Core Set 2021
“Adapt N” means “If this permanent has no +1/+1 counters on it, put N +1/+1 counters on it.”
May 3, 2019 · War of the Spark
To amass N means “If you don’t control an Army creature, create a 0/0 black Zombie Army creature token. Choose an Army creature you control. Put N +1/+1 counters on that creature.”