"Aamir can swim."
Translation:आमिर तैर सकता है।
Why is it wrong if you dont use है? In all others sentences this is not needed
है is always needed. The only time you can omit it is when the sentence is in present tense and it's a negative sentence. The same sentence in negative form: आमिर नहीं तैर सकता (Aamir can't swim)