As per the instructions from her "Mystery Midnight caller", Agent Nikita arrived at the Coffee Shop at 2:55 pm. As soon as she sat at a table, a slick-looking waiter walked towards her and gave her the menu card. When she opened it, instead of a list of dishes, a note popped out. She couldn't understand a word written. "It must be some sort of code", she thought. Suddenly, her cell phone beeped. She received a message from a "Private" number that said, "U equals A". Help Agent Nikita decode the coded message. Provide a detailed explanation along with your answer.