Monthly Edition
noun, の adjective
The moon edition is the monthly edition, since 月 also means "month."
げっかん
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
月刊誌『ベーコン』は、エープリルフールのジョークとして、「ノーベルベーコン賞はマミに授与された。」と報じた。
A monthly magazine named "The Bacon" reported that the Nobel prize for bacon was awarded to Mami as an April Fool’s joke.