Pendiente literally means "pending" or "hanging," but in this context, it refers to things that are "unresolved" or "outstanding" between two people.
Becky G uses it in the line, "Resolvemos todo lo que tenemos pendiente" (Let's resolve everything we have pending). It's an interesting word choice because it hints at a deeper, perhaps unspoken, history or tension between the two individuals, making the invitation to resolve things more intriguing than just a simple hangout.
TQM and ILY are the same three words twice, once in Spanish and once in English, and Becky G refuses to pick one. The song opens mid-code-switch with "¿Qué te parece si tonight" (What do you think if tonight) and keeps sliding between the two languages the whole way through. It is a night that has already gone on long enough. She dismisses his friends with "A tus amigos, bye-bye, bye-bye" (To your friends, bye-bye, bye-bye), then runs out of patience on the dance floor: "Papi, ¿qué estás esperando?" (Daddy, what are you waiting for?). Watch the clipped pa' in "Estoy puesta pa' ti" (I'm ready for you), a shortened para you will hear all over reggaeton.
The whole room is watching her and she could not care less. "Están mirándome a mí" (They are looking at me) is followed straight away by "Pero yo te miro a ti" (But I am looking at you), and the hook settles it with a blunt "Que se jodan todos" (Screw them all) before "A mí me gustas tú, yeah, solo tú" (I like you, yeah, only you). What comes next is meant to stay quiet. "Los que están talking about us" (The ones who are talking about us) get dodged by way of "Vamos por la puerta de atrás" (Let us go out the back door), and the song signs off by repeating its one condition three times over: "Lo hacemos otra vez, que nadie se entere" (We do it again, and nobody finds out).