Activated abilities contain a colon. They're generally written "[Cost]: [Effect]." Some keyword abilities (such as equip) are activated abilities and will have a colon in their reminder text. Triggered abilities (starting with "when," "whenever," or "at") are unaffected.

No abilities of artifacts can be activated, including mana abilities.

Collector Ouphe's ability affects only artifacts on the battlefield. Activated abilities that work in other zones (such as cycling) can still be activated.

If you control Collector Ouphe, you can't activate any abilities of your artifacts, even if you'd sacrifice Collector Ouphe as a cost to activate one of those abilities.