Are you sure that you have put the pt_BR language files (important the nomenclature) in the appropriate directories of the theme, or even in the wp-content / languages / themes / nomedotema-pt_BR ? If you are certain about these details and even though the translation has not been identified, it is likely that this term is not stated in your language file.
The most friendly and immediate way to do this is with the Loco Translate plugin. Through Loco you simply go to Loco Translate > Themes > Your theme > Desired language > and "Sync" pro plugin identify strings that may be missing.
If you want to change through HTML, just use an editor of your choice and have a search on all the files in your theme for the term you want to translate.
Sometimes it happens that the text is added inside the CSS through a content: "text" , give it an inspection to try to identify it as well.
Any questions, let's go there!