The official language of Myanmar is Burmese (known as Myanmar). Most of Burman's pronunciation derives from the old Pali language (in Buddha's time), but the language is Chinese-Tibetan related to Chinese and, therefore, tonal (the word's tone matters) and analytical (most words are a long syllable). It is written using the Burmese script, based on the old Pali script. Bilingual signs (English and Burmese) are available in most tourist areas. The figures are often written in Burmese script.
There are also many other ethnic groups in Myanmar such as Mon, Shan, Pa-O and many others who continue to speak their own language. There is also a large ethnic Chinese community of Yunnan origin, the most visible in the city of Mandalay, many of whom speak Mandarin. Some regions are also home to many Aboriginal communities that continue to speak several Indian languages. However, with the exception of the elderly, it is rare to find locals who do not speak Burmese.
Myanmar is a former British colony, and as English is still compulsory in kindergartens and primary schools, many Burmese people understand at least rudimentary English. Most well-educated middle-class Burmese speak English fluently, while in large cities like Yangon and Mandalay, many people know English well enough for basic communication. Hotel and airline staff, as well as people working in the tourism industry, generally speak an acceptable level of English. You can find more spoken English in Myanmar than in Thailand.