The locals in Vrindavan mainly speak Hindi. To impress the locals, you can greet them with 'Namaste' which means hello in Hindi. Also, 'Dhanyavad' means thank you. It's always helpful to know a few basic phrases like 'kripya' (please) and 'kahaan hai ye?' (where is this?). You can learn these basic words and expressions through language apps like Duolingo or Babbel, or you can take a quick crash course at a local language school.