Enfeiticei comes from the verb enfeitiçar, which means 'to bewitch' or 'to enchant'. It's a captivating word that evokes a sense of magic and being under a spell.
In the song, Jorge Ben Jor sings, "Por você eu me enfeiticei" (Because of you, I became enchanted/bewitched). He uses this word to express how deeply and irresistibly he fell in love, as if he were under a love spell cast by the other person. It's a much more evocative way to say 'I fell in love' and adds a unique, almost mystical, dimension to the lyrics.