Starbucks is a chain of stores that sell coffee. A chain is many stores owned by the same company. Many of the stores look the same, and all stores sell the same items, often at the same prices.
Starbucks started in Seattle, Washington in the United States in the early 1970s. There are over 9,000 Starbucks stores all over the world. Most of these stores are in the United States. Some American cities have many Starbucks stores. Starbucks is known for growing its number of stores fairly quickly, often to a point where there are two Starbucks within a few blocks of each other. They also sell different teas and ice creams.