Senda translates to "path" or "trail". While it can refer to a literal path, in this song, it's used metaphorically to represent a life's journey or a chosen direction in love.
The singer repeatedly states, "busco otra senda" (I'm looking for another path), indicating he desires a different kind of love and life than what the older woman offers. It's a more poetic and less common word than camino (road), making it stand out.
Maelo Ruiz's "Por Favor Señora" is a really interesting song where he's politely, but firmly, turning down an older woman's advances. He keeps repeating, "Por favor señora, no se me ofenda" [Please, madam, don't be offended], trying to soften the blow.
He sees her as "muy bella, es usted perfecta" [very beautiful, you are perfect], but he's looking for something different. He describes her as "Una flor artificial" [An artificial flower], preferring a "amor temprano, olor a fresa" [early love, the smell of strawberries] and "un amor natural, hierba" [a natural love, grass]. He's not into the fancy life she offers with "Fiestas, restaurantes y un concierto a las diez" [Parties, restaurants, and a concert at ten], or the expensive gifts like "visón" [mink] and "perlas" [pearls]. He's worried that if he were with her, he'd just be "Un joven y oscuro seductor" [A young and dark seducer]. It's a pretty blunt way of saying he wants a youthful, simple love, not a sophisticated one.