"Sat sri akal" is a greeting that is commonly used by people who follow the Sikh religion. It's made up of three words: "sat," meaning truth, "sri," meaning great, and "akal," meaning timeless or eternal.
So, when someone says "sat sri akal," they are essentially saying "eternal truth is great". It's a way for Sikhs to acknowledge the importance of truth and to greet one another in a respectful manner.
It's kind of like saying "hello" or "how are you?" but with a deeper meaning behind it. It's a way to show respect and honor for the Sikh faith and its values.