The national language is Bengali (Bangla) and is spoken everywhere in Bangladesh. It’s an Indo-Aryan language derived from Prakit, Pali and Sanskrit and written in its own script.
Many Bangladeshis only understand limited English such as basic affirmatives, negatives, and some numbers. Learning a few Bengali words ahead of your trip will prove very useful.
Two centuries of British colonisation has made local people to identify foreigners as either British or American, and to view them with curiosity. The first question you will probably be asked is ‘What is your country?’ (Desh kothay? in Bangla). If hawkers or rickshaw-wallahs are over-zealous, ‘Amar dorkar nai’ or ‘Lagbey nah’ means ‘No thanks’. If you don’t wish to give money to beggars, ‘maaf koro’ means ‘pardon me’ or you can apply a tricky concept saying ‘Amar bangthi poisha nai’, meaning ‘I have no change’.