This is the 2450th most frequent Polish word.
carlos
The word "carlos" is not Polish; it is a Spanish name.
The word 'Carlos' is used as a proper noun to denote the name of an individual.
Carlos jest moim przyjacielem.
Carlos is my friend.
Here 'Carlos' appears as the grammatical object of the verb, still as a proper noun.
Zawsze kiedy rozmawia z Carlosa, śmieje się.
Whenever she talks to Carlos, she laughs.
In this sentence, 'Carlos's' denotes possessiveness, showing ownership of the car.