The word another means one more of something, or a different one from what you already have or know about.

When your glass of lemonade is empty and you ask for another, you want one more glass. When you finish reading a book you loved and immediately reach for another by the same author, you're choosing a different book but hoping for the same satisfaction. If your friend suggests watching a movie you've already seen, you might say, “Let's pick another one,” because you want something different.

The word combines the idea of “one more” with “not the same one.” If you solve a math problem and your teacher says “try another,” she means do one more problem, and it will be a different problem from the one you just finished. When someone says “that's another story” or “that's another matter entirely,” they mean the new topic is separate and different from what you were just discussing.

Another helps us talk about both quantity (one more) and variety (a different one) at the same time, which makes it surprisingly useful in everyday conversation.