Francesinha literally means 'little French girl', but in Portugal, it's the name of a famous and hearty sandwich from the city of Porto. It's typically made with bread, ham, sausage, and steak, then covered with melted cheese and a hot tomato and beer sauce.
In the song, the singer from the north of Portugal uses this iconic dish as a metaphor for his life in Lisbon. He sings, "A francesinha já não tem picante" (The francesinha has no spice anymore), to express that without his love, everything that was once flavorful and exciting has become bland and tasteless.
This song is all about a feeling the Portuguese call saudade—a deep, painful longing for someone you love who is far away. The singer has moved from the north of Portugal to the capital, Lisbon, to chase a dream, but he's not sure it's going to work out. He sings, "Eu vim do norte direto a Lisboa / Atrás de um sonho que eu nem sei se voa" (I came from the north straight to Lisbon / Chasing a dream I don't even know if it will fly).
Everything in the big city reminds him of his love, Maria Joana. Even the food is a disappointment! He complains that "A francesinha já não tem picante" (The francesinha doesn't taste spicy anymore), a classic dish from his home region. This lack of spice makes him remember the passionate moments they shared. He's so lonely and homesick that he begs her, "Maria Joana / Apanha o primeiro autocarro / Vem ficar p'ra sempre do meu lado" (Maria Joana / Catch the first bus / Come stay forever by my side). It's a simple, desperate plea from someone who is realizing his dream means nothing without the person he loves.