You’re not translating the verb है. The construction subject+verb clause (where कलाहै would be the verb clause) is common and that’s what you have here.
I don’t believe there is any way to get grammar information on the app, which I find really lacking. IMHO, giving access to the forums and/or grammar content should be a priority for Duolingo. That said, there is not much grammar information so far in the Hindi tree: it’s still in beta.