Confiésame is the command form of the verb confesar (to confess), with "me" attached, literally meaning "confess to me". It’s a powerful and intimate plea that you don't hear in every song.
In "Poema", the singer uses this word to passionately urge his love interest to admit her feelings, singing "Confiésame tu amor" (Confess your love to me). This single, dramatic word perfectly captures the romantic tension at the heart of the song.
This song is a direct and confident attempt to escape the friend zone. The singer is talking to a girl he's known for a while, saying, "Llevas tiempo hablando conmigo / Y no sabes quiero ser más que un amigo" (You've been talking to me for a while / And you don't know I want to be more than a friend). He's tired of waiting and wants her to admit her feelings, which he's already sure she has for him. He's not shy about it at all, telling her, "Yo sé que me quieres / Sólo dilo para oírlo" (I know you want me / Just say it so I can hear it).
He mixes sweet, romantic lines with very forward compliments. One moment he's saying he cleared his whole schedule just to write her this song, "Desocupé mi día pa' escribirte esta poesía" (I cleared my day to write you this poem). The next, he's telling her exactly what he likes about her body, like "Me encanta tu cinturita" (I love your little waist). He senses she might be hesitant or shy, so he encourages her to speak her mind without a filter and trust him, promising that "como yo no hay otro" (there's no one else like me).