The official language of Thailand is Thai.
English is widely spoken in Thailand, particularly in tourist areas and by those in the hospitality industry, but the further away you go from main areas the less English you will be offered.
There is no official religion in Thailand although the majority of Thais practice Buddhism of some kind. Islam, Hinduism, and Taoism are also practiced to a lesser extent.
Songkran or Thai New Year is celebrated from the 13th-15 April each year. It celebrates a fresh start and the new seasons so water is used for cleaning statues of Buddha and family members. This also descends into a water fight on a national scale and for three days children walk the streets with water guns and everyone gets soaked.
Loy Krathong, the Festival of Light is celebrated every November. The festival is used as a time to put the past behind you and wish for a positive future ahead. Floating offerings with lighted candles in them are placed in a river and a wish recited. If your offering sinks then your wish won’t come true that year, but if it floats away with the candle still lit then it will come true.