What are the chances of not picking a club out of 52 cards?

One quarter of the pack are CLUB cards. Three quarters of the pack are NOT CLUB cards.

So the chance (probability) of picking a CLUB card is 1 out of 4 = 0.25

The chance (probability) of picking a NOT CLUB card is 3 out of 4 = 0.75

Adding the various probabilities the answer must always be 1.0, which is true here.

If the probability of something happening is 1.0, that means the probability is "certainty". It is bound to happen.