This is the 1218th most frequent Dutch word.
sergio
"Sergio" is not a Dutch word; it is typically a personal name.
In this sentence, 'Sergio' is used as a proper noun, referring to a specific individual undertaking an action.
Sergio gaat naar de winkel om brood te kopen.
Sergio goes to the shop to buy bread.
Here, 'Sergio' is again used as a proper noun, placed in a possessive construction to show the relationship.
Mijn vriend Sergio houdt van reizen naar exotische locaties.
My friend Sergio likes traveling to exotic locations.
The word 'Sergio' identifies the subject of the sentence who is involved in an activity, continuing the use as a proper name.