Thai
Thai (historically known as Siamese) of the Kra-Dai language family is the sole official language of Thailand, where it’s spoken by over 69 million people.
It’s an analytic, SVO, tonal language with a unique writing system similar to other writing systems on the Indian sub-continent (and more distantly related even to the alphabet English uses!).
Learning Thai presents a unique challenge due to the different language family from English, different script, and tones, but if you work hard at it every day and reference the articles on Perfect Polyglot, you’ll be speaking it in no time!