It's not a general “Congratulations.” While it serves the function of congratulations at a wedding, it is not a direct translation of the word. The general term for “congratulations” is
恭喜 (gōngxǐ), which is used for promotions, graduations, having a baby, etc. At a wedding, it's very common to combine them: “恭喜恭喜!新婚快乐!” (Gōngxǐ gōngxǐ! Xīn hūn kuài lè!).