Ligb stands for "Let it go bro".
The word, pronounced as written, is used to
tell someone to move on from something and
literally let it go.
Bro: I miss my ex so much bro, I want to go back with her
You: You have to ligb her bro, it’s over.
Bro: Dude I always think about our
trip in the summer, that was so
fun man.
You: Ligb it, it’s the semester, we need to focus