Oracle Text

Counter target activated ability. (Mana abilities can't be targeted.)

Draw a card.

Card Rulings

12/1/2004 Squelch can’t target a mana ability because mana abilities don’t use the stack.
6/8/2016 Activated abilities contain a colon. They’re generally written “[Cost]: [Effect].” Some keywords are activated abilities and will have colons in their reminder text.