Translation:You can swim.
is QallaH always coupled with 'can' or can it also be an infinitive 'to swim'?
Since this is a learning environment, I want to make a few corrections there. The first word is Qapla'. Note that the Q and q are different letters in Klingon. It probably would have been more convenient if Dr. Okrand had used a k instead of a q, so it would be clearer that they are separate letters with separate pronunciations, but we are stuck with it now. The second letter should be a, not u. And there must be a ' at the end of the word. In English, the ' is a grammatical mark so we give less importance to it and are less concerned when we leave it out of a word. However, in Klingon ' is a full letter, like a "t", and the word is misspelled with out i.
Also, Qapla' and batlh are both nouns and so you must use a noun conjunction to join them: Qapla' batlh je.