Pumping lemma regular language can't be pumped Suppose we have a regular language that describes every string with the exact length of 3.That is obviously a regular language and it still can't be pumped because there is no cyclic behavior in that string/ the corresponding dfa

Can you please help me figure out my mistake?
Have a look at the exact wording of the pumping lemma: It has a precondition that only words exceeding a certain size need to be pumpable. This is exactly so that only words with repetitions have to be pumpable.

For your language (and every other finite one) you can simply set that size beyond the maximum word size (e.g. at 4). No words are longer than that, and all of them can be pumped.