Welcome, the walter. I like your name.
Sell tail means to prostitute oneself. Tail refers to three things. The one the speaker below is referring to is the second one listed under 1. tail here: Urban Dictionary: tail a girl's ....
From The Bluest Eye by Toni Morrison“Oh, Lord. How that man loved me! Then why he left you to sell tail? Girl, when I found out I could sell it - that somebody would pay cash for it, you could have knocked me over... my auntie whipped me good that first time when I told her I didn’t get no money. ..Money? For what? He didn’t owe me nothin’... The hell he didn’t!”All the best.