Traditional food for Beijing, China -------2------ Glutinous rice ball

Snack bars of in Beijing sell Gglutinous rice balls around the Spring Festival of China, they would sell this kind of food until late summer or early fall in ancient times. (This sentence sounds a bit awkward in the way that you've written it right now. A better way to say this would be: In ancient times, Beijing snack bars sold (past tense) glutinous rice balls from the time of the Chinese Spring Festival to late summer or early fall.) But Nowadays, however, the food will be is sold all the year around. (The phrase is "all year round.")
A glutinous rice ball is made by with sticky rice, and it belongs to the Muslim flavor (I'm not really sure what this means?). It looks like a white ball, with a soft texture with and sticky quality, and it tastes sweet.

Hi! Great job on this! I know it looks like I made a lot of corrections (sorry!), but it's just because of the first sentence. After that, it's just small things. Although it can be a stylistic choice, starting sentences with words like "but" or "and" isn't really standard English grammar. In addition, I added "nowadays" to differentiate from "ancient times" to now. For entities like "glutinous rice balls," if you're talking about the object as a whole, such as describing the whole group, you should either say "Glutinous rice balls" (plural) or "A glutinous rice ball" (singular). Let me know if you have any questions!

Traditional food for Beijing, China -------2------ Glutinous rice ball

Beijing snack bars of Beijing sell Glutinous rice balls around the the time of Spring Festival of China; they would sell this kind of such food until late summer or early fall in ancient times, but in modern times the food will be it is sold all the year round.
A/The glutinous rice ball is made by with sticky rice and it belongs comes from (really? but tangyuan are not, are they?) to Muslim origins flavor. It looks like a white ball, and is soft textured with sticky quality, and is sweet taste sweet.