This is the 6749th most frequent Portuguese word.
gianmarco
"Gianmarco" is not a Portuguese word; it is an Italian given name.
The word 'Gianmarco' is used here as a proper noun, specifically a name of a person.
Gianmarco é meu amigo desde a escola.
Gianmarco has been my friend since school.
The word 'Gianmarco' is used as the subject of the conversation, emphasizing it as the entity being referenced.
Ontem, conversei com Gianmarco sobre o projeto.
Yesterday, I talked to Gianmarco about the project.
Here, 'Gianmarco' is used to directly identify the person performing the action of planning, again as a proper noun.