Western clothes are easier to work in than Japanese clothes.
Literal
Western-clothes [topic-は] Japanese-clothes than work-easy.
洋服 ('Western clothes') contrasts with 和服 ('Japanese clothes / traditional kimono and its variants'). This 洋/和 distinction runs through Japanese vocabulary: 洋食/和食 (Western/Japanese food), 洋室/和室 (Western-style/Japanese-style room). より is the comparative particle. 働きやすい uses the ~やすい pattern.