Here's a breakdown:
* Brimming: means to be full to the top, almost overflowing.
* Over: suggests that the emotion is so strong, it's about to spill out.
Examples:
* "She was brimming over with joy after seeing her family."
* "He was brimming over with excitement about his upcoming trip."
* "The room was brimming over with love and laughter at the wedding."
The idiom emphasizes the intensity and abundance of the emotion. It suggests that the person is experiencing a truly overwhelming feeling.