From Wikipedia:
"Ederlezi" is a popular traditional folk song of the Roma minority in the Balkans.
The song got its name after Ederlezi which is a Spring festival, especially celebrated by Roma people in the Balkans (and elsewhere around the world). This holiday celebrates the return of springtime. Ederlezi is the Gypsy name for the Serbian Feast of Saint George. It's celebrated on the 6th of May. The various Balkan spellings (Herdeljez, Erdelezi) are variants of the Turkish Hıdırellez, a holiday signaling the beginning of spring, occurring approximately 40 days after the spring equinox.