If you are travelling to another country, however short a period of time it might be for, it is always a good idea to learn some of the language if you can. You might well find that many people there already speak English – it is the most widely spoken language in the world. However, it never does any harm to learn some of the local language as well.
If you do find yourself in a situation where someone doesn’t speak English, it is going to be very helpful speaking some of their language. You might find you need to ask for directions, or you might be travelling to somewhere more remote where people don’t speak English as much.
It also shows that you appreciate the culture of the country and it is very polite to speak to someone in their own language. Even if you find you don’t need these language skills, it is a nice gesture to have them.