A New Day in the Old Town - S2-E1
Corrected entry: Peter tells Olivia that the Greek phrase she said on waking up was "Na einai kalytero anthropo apo ton patera tou" and translates this as "Be a better man than your father." The Greek is grammatically incorrect (it should be "kalyteros anthropos...") and Peter's translation is wrong. The translation of Olivia's phrase is "May he be A Better Human Being than his father." What Peter said is a translation of the Greek phrase "Na eisai kalyteros anthropos apo ton patera sou." (00:37:40 - 00:38:25)
Correction: His mother was making a wish. No one said it directly translates as anything. He says "It means." Referring to its meaning for him personally, to fulfill his mother's wish. Also she may have simply told him as a child a simple meaning for him to relate to. Knowing (Peter's mum) Elizabeth's character from later in the show, that seems very likely in its own right.