A belt is a release of gas. Gas exited through your mouth, so when this location is called a bean belt, it is referring to how coffee beans are exiting their original location, like a burp does. (This purely in my opinion, I have no knowledge of this.)
You use expression by explaining your feeling in writing form. Sadness is one of the most expressed feelings in writing. Here is a site to get you an idea if you want to write a story:
https://www.scoopwhoop.com/saddest-lines-from-literature/#.fs19fnc37
Hope it helps!!!
It seems that you have missed the necessary details for us to answer this question, but hope this would help you. The line in the given passage that is considered a flashback is this: <span> She thought of her last day in middle school, seven years ago, when Sarah had given her an iPod. Have a great day!</span>
