Büyülendim means "I was enchanted" or "I was mesmerized." It comes from the root word "büyü," which means "magic" or "spell."
In the song, the artist uses this word to describe the powerful and almost magical effect someone had on him at first sight: "Ama seni görüp büyülendim" (But seeing you, I was enchanted). It's a more evocative and less common way to express being captivated, making it stand out from typical expressions of attraction.
BLOK3's "Aklına Ben Gelicem" is a really intense song about a love that went wrong, and the singer's refusal to be forgotten. He starts by admitting that falling for this person wasn't planned, but he was completely captivated: "Aslında hesapta yoktu / Ama seni görüp büyülendim" [Actually, it wasn't in the plan / But I saw you and was enchanted]. They became a couple, and he was so sure no one could come between them. But then something happened, something that changed her, and he saw it happen right before his eyes. He says, "Sevdiğim kız hala yaşıyor evet / Ama benim sevdiğim o hali öldü" [The girl I loved is still alive, yes / But the version of her I loved died].
He's clearly heartbroken and a bit possessive, vowing that no matter what she does or who she's with, he'll always be on her mind. He repeats, "Birini bulunca aklına ben gelicem / Elini tutunca aklına ben gelicem / O şarkı çalınca aklına ben gelicem / Unutma aklına ben gelicem" [When you find someone, I'll come to your mind / When you hold their hand, I'll come to your mind / When that song plays, I'll come to your mind / Don't forget, I'll come to your mind]. It's a pretty blunt statement, and he even goes as far as to say, "Bi gün başkasını bulursan / O gün kendimi öldürücem" [If you find someone else one day / That day I will kill myself]. This song is a raw look at the pain of a love lost and the desperate hope that he'll forever haunt her thoughts.