Djurdjevdan, Serbian for George’s Day, was released in 1988 by Bijelo Dugme and it is a cover of the Romani song Ederlezi, a song about the beginning of the spring.
Its lyrics are way different than the original Ederlezi song and you can find them here.
Here’s a great version from Jelena Tomasevic & Goran Bregovic:
And the Ederlezi song by Vaska Jankovska: