"This is a foreign holiday" is a correct way to say "这是外国的节日" in English. You could also say "This holiday is from a foreign country." If you are looking for a specific holiday, you can say "This is (holiday name) holiday," for example, "This is Christmas holiday." If you are looking for a way to ask about a holiday, you can ask "What holiday is this?" or "What is this holiday called in English?"
