Palomo literally means "pigeon." However, in many Latin American countries, including Puerto Rico where Farruko is from, it's also used as slang to describe a naive, gullible, or easily fooled man.
In the song, the lyrics state, "El día que un palomo la engañó" (The day a 'palomo' deceived her). This implies she learned a valuable lesson after being tricked by a naive or foolish man, making the word a clever and culturally specific choice.
"Anda Sola" is built around one line, repeated like a thesis: "Mejor anda sola, que mal acompañada" [Better to walk alone, than in bad company]. Farruko is describing a woman who has stopped negotiating on herself. She has her own money ("No hace falta que le gasten, ella se puede costear" [No need to spend on her, she can afford herself]), her own faith ("Que amor sin Dios ya no dura" [That love without God no longer lasts]), and a clear read on people ("Tiene la visión bien clara, y con ninguna se compara" [She has a very clear vision, and compares to none]).
None of this is abstract. She got hurt before, "El día que un palomo la engañó" [The day a fool deceived her], and the song credits that exact moment for who she is now: "El golpe le enseñó a ser más fuerte" [The blow taught her to be stronger]. So when a guy shows up only "pa' después dejar la milla" [to then leave the mile], she's already gone, and when people throw shade her way she doesn't argue back, "su bendición es lo que ella regala" [her blessing is what she gives]. Walking alone, here, isn't a fallback. It's the standard she's holding out for.