It is a little tough to translate, because it is an expression that has its best intent within the language itself. Literally, it means "Oh my time!" However, this makes very little to no sense in English. The meaning should be closest to saying "Oh, how I long for you, my era (or my time)!" or "Oh my time (of my youth) have passed." Althought this doesn't hit the nail on the head exactly in terms of its meaning, but I believe it is close enough to get the idea of what the phrase is trying to express. I also believe context is very important to understand what the author/speaker is trying to convey. Best of luck!