A piece of cake - This idiom means that something is very easy to do.
Example sentence: "I thought climbing the mountain would be difficult, but it turned out to be a piece of cake."

Bring home the bacon - This idiom means to earn a living or provide for a family.
Example sentence: "I work hard to bring home the bacon for my family."

Cry over spilled milk - This idiom means to get upset over something that has already happened and cannot be changed.
Example sentence: "There's no point in crying over spilled milk; let's just clean it up and move on."

In a nutshell - This idiom means to summarize something in a few words.
Example sentence: "Can you explain the plan in a nutshell so I can understand it quickly?"

A taste of your own medicine - This idiom means to experience something negative that is similar to what you have inflicted on others.
Example sentence: "After always teasing her classmates, she finally got a taste of her own medicine when they played a prank on her."