Catira is a unique and endearing term for a blonde woman, primarily used in Venezuela and some other parts of Latin America. It's not a common word you'd hear in every Spanish song, making it stand out.
In the song, ELENA ROSE uses it affectionately when she sings, "Ya tú sa'e que me encantas, catira" (You already know I enchant you, blonde). This adds a personal and charming touch, highlighting a specific characteristic of the person she's singing to.
The title is a timetable, and Elena Rose means it literally. She books the whole week in advance: "Que quererte to' los lunes / Y comerte to' los martes" ("Than love you every Monday, and devour you every Tuesday"), carries on through "miércoles, jueves y viernes" ("Wednesday, Thursday and Friday"), fits in "Piquito en todas partes" ("Little kisses everywhere"), and by Saturday the plan is already "Nos vamos pa' la playita" ("We'll go to the beach"). Nobody has agreed to any of this. She has filled in the calendar and left him to catch up.
That is the trick of the song. They have barely met, and her excuse is that it does not feel that way: "Si ya se siente como si nos conocemos" ("If it already feels like we know each other"). Manuel Turizo turns up with a lot less patience and promises "toda la ropita te voy a quitar" ("I'm going to take off all your clothes"), while the chorus keeps handing the blame to an organ that cannot defend itself: "Ay, mi corazón se enamoró / Y ahora solo late por ti" ("Oh, my heart fell in love, and now it only beats for you"). Convenient.