selvi - cypress (tree)
boylum - lit. "my height" (from "boy" - height)
But together "selvi boylum" comes to the meaning of "my one as tall as a cyprees tree". It is a turkish way to address a girl one likes,i.e "you are my tall girl, tall as a cypress tree".
al - red, scarlet, crimson (color)
yazmalim - lit. "my scarf" (from "yazma" - hand-painted scarf, or cloth that has been painted or printed by hand)
So together it means
"(You are my girl) as tall as a cypress (tree), (you are) my scarlet scarf..."
It is a very turkish way to express one's affection for somebody... sort of playful flirtous language...