"Bravo Zulu" is a term from naval and military communications, specifically in the NATO phonetic alphabet. It means "Well done" or "Good job."
The phrase comes from the signal flags used by naval forces, where "Bravo" and "Zulu" are used to represent the letters "B" and "Z." When these flags are flown together, they form the signal that conveys approval or praise for a job well done.
In a broader sense, it can be used as an informal way to express congratulations or to acknowledge someone’s successful effort.
