The writer is saying that when you return to your hometown, you realize that the nostalgia you feel isn't for the physical place, but for the stage of life you were in while living there (childhood). The author might be referring to the sense of joy and innocence in childhood.

" When you finally go back to your old hometown, you find it wasn't the old home you missed but your childhood" you find it wasn't the old home you missed but your childhood" means you will find it wasn't the old home you missed but IT WAS YOUR CHILDHOOD (that you actually missed)

The quote assumes you don't live in the same town you grew up in (your "hometown"). It suggests that you have missed/longed for your hometown and decided to go back there. However, when you return, you realize that you didn't really miss your hometown. You missed your childhood - it's really your childhood you longed for. I think it would be something like this in Spanish: Cuando, finalmente, se vuelve a su ciudad natal, te das cuenta de que no era la antigua casa se ​​ha perdido, pero su infancia

Sorry!! and thank you for the correction!

"Do you know what this quote means?"