This is the 7242nd most frequent Polish word.
joao
The word "joao" is not Polish; it is typically a Portuguese name. It does not have a distinct meaning in English as a Polish word.
This usage of 'Joao' is as a proper noun, serving as the subject of the sentence.
Joao widzi kota w parku.
Joao sees a cat in the park.
Here 'Joao' is the narrator and subject of the verbal action, demonstrating narrative context.
W książce Joao opowiada o swojej podróży.
In the book, Joao tells about his journey.
In this case, 'Joao' appears in a communicative and direct-address context.