Learn Portuguese (Portugal): O adulto trabalha e o aluno estuda. - The adult works and the student studies.

They are the he, she, or it (third-person singular) forms of the regular -ar verbs trabalhar (to work) and estudar (to study). In the present tense, you drop the -ar and add -a for this form.

Could I use adulta and aluna if I were talking about females?

Yes! Both nouns change their ending to match the gender of the person. A female adult is a adulta, and a female student is a aluna.

I have also seen the word estudante for student. Is it interchangeable with aluno?

They are very similar, but aluno usually refers to a pupil at a primary or high school, or a specific teacher's student. Estudante is more often used for older students, like those at a university, but you will be understood using either one at this level.

How do you pronounce the word e (and) in this sentence?

The Portuguese word e meaning and is usually pronounced like the ee sound in the English word see.