noun
A ring of flowers or leaves used for decoration, celebration, or memorial purposes.
クリスマスに玄関に花輪を飾った。
We hung a wreath on the front door for Christmas.
優勝者に花輪が贈られた。
A garland was presented to the winner.
リース is a loanword from English 'wreath' and often refers specifically to Western-style decorative wreaths, while 花輪 is a more general Japanese term for any floral ring or garland.
Compound of 花 (flower) and 輪 (ring, circle). The spelling 花環 uses 環 (ring, circle) with a similar meaning.