He wanted her to prove her improved Hindi-speaking skills.
Katrina and "Jhalak Dikhhla Jaa" contestant Shibani Dandekar have a tough time speaking in Hindi. However, they have been trying hard to brush up their skills, and believe they have improved a lot.
So, when Salman challenged them to speak in Hindi, Katrina said: "Aap kaise ho (How are you)", to which Shibani replied: "Main ache hai (I am fine), How are you?"
It was enough to impress Salman and he gave the girls a standing ovation!