Activated abilities contain a colon. They’re generally written “[Cost]: [Effect].” Some keywords are activated abilities and will have colons in their reminder text.

Doesn’t skip the Combat Phase, just renders creatures unable to attack.

Can be cast after your attack.

It affects the current turn and the next turn. This could affect the same player twice if they have two turns in a row, or it could affect different players. In a multiplayer game it affects exactly two turns, not a full round of turns.