This is the 4112th most frequent Chinese word.
反共
"Oppose communism" or "anti-communism."
Here, '反共' is used as an adjective describing a policy opposing communism.
许多国家有反共的政策。
Many countries have anti-communist policies.
In this context, '反共' functions as a verb meaning 'to oppose communism' with direct action implied.
一些团体积极地站出来反共。
Some groups actively stand out to oppose communism.
Here, '反共' is used as a noun to describe an ideological standpoint against communism.