Activated abilities contain a colon. They're generally written "[Cost]: [Effect]." Some keywords are activated abilities and will have colons in their reminder text.
Quicksilver Elemental
The granted abilities effectively use "this permanent," rather than "[that card's name]," so you treat the abilities as if they were printed on Quicksilver Elemental. For example, you treat an ability that says "Sacrifice a creature: Nantuko Husk gets +2/+2 until end of turn" as "Sacrifice a creature: Quicksilver Elemental gets +2/+2 until end of turn."
Quicksilver Elemental can gain the activated abilities of any creature on the battlefield that you can target with its ability, even if you don't control that creature.
Magic: The Gathering · ™ & © Wizards of the Coast · Illus. Tony Szczudlo
Card data via Scryfall. Rarix is fan-made; not endorsed by the rights holders.
