The fall festivals in Japan are held to give thanks to god for the good harvests.
Japanese people have fall festivals as a means of saying thank you to god for a plentiful fall harvest.
ーThe fall festivals in Japan are held to give thanks to god for the good harvests.
「日本の秋祭りは神様に豊作を感謝するために行われる」
fall festivals で「秋まつり」
to be held で「行われる」
to give thanks で「感謝する」
good harvests で「豊作」
ーJapanese people have fall festivals as a means of saying thank you to god for a plentiful fall harvest.
「日本人は秋の豊作を神様に感謝する手段として秋祭りを行います」
a means of ... で「…の手段・方法として」
plentiful fall harvest で「秋の豊作」
ご参考まで！
カナダ 
