It's simple. There's a kigo part and a free format part to the kukai. People can enter one or both. By entering one or both of them, entrants then can vote anonymously on their favorites of the haiku entered.
The kigo for May is "long day." This means that "long day" should be used seasonally in your haiku. Entries should be e-mailed to email@example.com with a subject of "kigo entry."
The free format word is "bucket/pail." This means that the word bucket(s) or pail(s) should be used somewhere in your haiku. Entries should be e-mailed to firstname.lastname@example.org.
There isn't much time left, but if you're a last-minute adrenaline type person, what are you waiting for?