Sensacional translates directly to "sensational" in English. It's a vibrant and enthusiastic adjective that perfectly captures the feeling of something extraordinary and exciting.
In the context of Tim Maia's song, the singer uses it to describe a casual encounter that turned out to be surprisingly amazing: "Que seria assim sensacional" (That it would be so sensational). It highlights the unexpected joy and intensity of the romantic connection, making it a memorable and enticing word for learners.
"Você E Eu, Eu E Você" is Tim Maia at his warmest: a song built almost entirely around one simple idea, said every possible way round. "You and I, I and you" isn't really a lyric to be analysed line by line, it's a refrain to be felt, and Tim leans into that by turning the whole thing into a singalong.
The verses fill in a little more of the story: a chance meeting that somehow felt like it was always going to happen, and the giddy realisation that it turned into something wonderful. From there the song stops being about explaining and just becomes about celebrating, going out to dance, share dinner, and fall asleep together, with the crowd shouting the chorus right back at him.
It's less a love song about longing and more one about already having found each other, and just wanting to say so, over and over.