noun, な adjective, の adjective
Remember how 風 can mean "style" as in 和風? Well, this is now Western style style, more simply put as Western style.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
Tonight's supper is Western style pot‐au‐feu.
A refined western-style song was played in a Western style cafe.
My house is entirely furnished in the Western style, so there are no tatami mats.