This is the 8642nd most frequent Portuguese word.
adulta
Adult (feminine).
Here, 'adulta' is used as an adjective describing 'pessoa', denoting maturity.
Ela agora é uma pessoa adulta.
She is now an adult person.
In this case, 'adulta' serves as an adjective describing 'discussão', highlighting the maturity of the dialogue.
A discussão foi muito adulta e respeitosa.
The discussion was very mature and respectful.
Here, 'adulta' modifies 'maneira', suggesting behavior expected from a mature person.