Most words for people have a masculine and a feminine form: -o becomes -a (o amigo, a amiga; o vizinho, a vizinha), and a word ending in -or adds -a (o professor, a professora). The article and any adjective change with it: uma vizinha simpática.
Examples
- O Rui é um amigo da escola.
- Rui is a friend from school.
- Tenho uma vizinha muito simpática.
- I have a very nice neighbour.
- A professora da minha filha é jovem.
- My daughter's teacher is young.
The mistake to avoid
Some never change, and only the article shows who is meant: o estudante, a estudante; o jovem, a jovem.
Where this fits in
Family & people, Portuguese A1: Talk about your family, say what people are like and how old they are, and introduce your friends.