而已 (ér yǐ) is a sentence-final particle meaning that's all or nothing more. It downgrades or minimises what has just been said, making a statement seem less significant. It frequently pairs with 只 (zhǐ, only) or 不过 (bù guò, merely): 只是...而已 (it's just... that's all). The phrase has a slightly literary flavour compared to the colloquial 罢了 (bà le), which carries the same meaning.