It’s a short poem, full of alliteration. It means that the first letter which is used in the first word of a particular line is used to make all the words of that line. For example: The first letter of the first line of this poem is ‘F’, so every word of the same line starts with ‘F’ and the meaning is also conveyed. The same rule is applied on the other lines.

Falling feathers from falling flowers
Wither woefully with wintry wash.
Seeing such strange snow shower,
Bill’s brain became blankly bald.