Pink cherry petals,
Delivering spring’s blithe air,
Through the cool March wind.

A haiku is a 17-sound poem (5, 7, 5)that originated from Japan. Incidentally, "seasons" is a common topic on which haikus were written. Also, as cherry blossoms were a favorite of the Japanese, they were a common topic in their poems.
March is a spring season. In Vancouver, one can often see cherry blossoms decorating their surroundings.
"Delivering", an action by the petals, is personification.