Ébloui means "dazzled" or "blinded by light." It's a vivid and evocative word that goes beyond a simple "impressed" or "amazed."
In the song, Stromae sings, "J'ai dû me lever tôt pour être ébloui" (I had to get up early to be dazzled). He uses it to describe the intense, almost overwhelming feeling of being struck by the summer sun, despite his concerns about skin cancer. This word perfectly captures the bittersweet intensity of his summertime experience.
Stromae spends this song trying to finish one sentence, and the chorus never lets him. Every verse runs up to the same words — "Car ça me stresse que quelque chose vienne gâcher mon" (Because it stresses me out when something comes to ruin my) — and then the missing word arrives in English and repeats until it stops meaning anything.
The holiday it describes was bought rather than enjoyed. "J'ai bossé dur pour me le payer" (I worked hard to pay for it) is followed by "Là je sue car il faut en profiter" (There I'm sweating because you have to take advantage of it): the sun is an obligation with a receipt attached. He got up early for it, and what he gets is "Être ébloui et mon cancer de la peau" (Being dazzled and my skin cancer). Then he looks up — "Le ciel est bleu, ou plutôt gris bleu" (The sky is blue, or rather gray-blue) — and looks sideways at what is happening just off the postcard: "À cent mètres à peine, certains survivent" (Barely a hundred meters away, some survive).