Stands for "Take the loss". Frequently used to describe flunking a test, being dumped, being stood up, being beaten up or robbed, or losing one's money in the stock market, gambling, or through exploitative business schemes.
Take No L's, the term meaning one who takes no loses and avoids rejection. Basically a savage.
Bruh 1: Yo Bruh, we taking no L's at the club tonight.
Bruh 2: Yea Take No L's, we not getting stood up.
Bruh 1: And we gon turn up... Straight Savages