Bahasa Indonesia is a language belonging to the Austronesian family of languages and a little more precisely, the Malay group of languages. It's spoken by 40-45 million, mainly in Indonesia, and it's quite an interesting language!
Many languages in Asia, like Mandarin Chinese, Vietnamese, and Thai use tones when pronouncing words. Tones are different changes in the pitch with which a syllable is pronounced, and because of this it's extremely important to pronounce words with the right tone, or you'll simply not be understood (or you'll be misunderstood!)
But just because a language is spoken in Asia, doesn't mean that it uses tones. Japanese is not a tonal language, and while Korean used to be tonal, the language spoken today is not considered to have tones. The same goes for Arabic, which definitely isn't tonal.
So what about Indonesian?
Indonesian is not a tonal language. Tonal languages are rare in the Austronesian language family, but they do exist, such as the Tsat language. The Indonesian language has a tendency to stress the last, or second-last syllable of a word, however, but this cannot be considered an example of tones, because the stress does not change the meaning of a word.
The fact that the language isn't tonal is another argument to the relatively low difficulty of Bahasa Indonesian. Indonesian is regarded by many as one of the easier world languages that one could set out to learn, even if it's completely unrelated to English. The fact of the matter is that Indonesian has a delightfully simple grammar-system, easy pronunciation, and vocabulary that makes sense, which is why a lot of people decide to learn Indonesian - a language that keeps giving, especially for someone who likes traveling!