Date format and some text translations

I’d like to translate some texts to my idiom and change date format of the post dates. For sample, in the date it shows “Apr 22”, but I need to translate not only the texts but the format to “22 Abr”. Also swap button text “Read more” for “Leia mais” and “No comments/X comments” to “Sem comentários/X comentários”.

I found in this support forum some clues of how but not where. Where do I find these codes to make text the changes? Thanks.