Okay, the user sent "pay-day". Let me check the translation rules again. The first rule says to translate all content into Vietnamese. The second rule states that if the content is already in Vietnamese, leave it unchanged. The third rule is to provide only the translation result without explanations.
So, "pay-day" is an English term. The Vietnamese equivalent for "pay-day" is "ngày lương" or "ngày lĩnh lương". I need to make sure which one is more commonly used. "Ngày lương" is straightforward, while "ngày lĩnh lương" might be more specific, referring to the day when one receives their salary. Depending on context, but since the user just provided "pay-day" without context, "ngày lương" is probably the safer choice.
Wait, maybe "ngày lương" is more like the salary day in general, whereas "ngày lĩnh lương" is the actual day of receiving it. But in many cases, people might just use "ngày lương" as the common term. I'll go with "ngày lương" for the translation. Let me confirm with some examples. If someone says "pay-day is every Friday," translating to "ngày lương là vào mỗi thứ Sáu" sounds correct. Alternatively, "ngày lĩnh lương" could also work, but "ngày lương" is more concise.
Since the user wants only the translation and no explanations, I should just provide "ngày lương" as the response. No need to add anything else. Make sure there's no extra text, just the translation.