IDIOMATIC EXPRESSION WITH THE VERB "SER" - 2 :

"SER" from /of .
This is used for ‘to be from (a place)’, ‘to be made of (a material)’, ‘to be one to (do some -
thing)’:

Você é de onde?
Where are you from?

As casas eram de madeira.
The houses were built of wood.

O Zé não é de beber.
Zé is not one to drink.

Ref.: Modern Brazilian Portuguese Grammar - A Practical Guide.