English says I have a dog. Finnish has no verb “to have” at all. Instead it says, literally, “at me is a dog”: the owner takes the ending -lla / -llä (at, on), and the verb is simply on (is).

Pronoun	“at …”	Example	English
minä	minulla	Minulla on koira.	I have a dog.
sinä	sinulla	Sinulla on kissa.	You have a cat.
hän	hänellä	Hänellä on talo.	He / she has a house.
me	meillä	Meillä on aikaa.	We have time.
te	teillä	Teillä on auto.	You have a car.
he	heillä	Heillä on pyörä.	They have a bike.

Names work the same way: Marcosilla on koira. — Marcos has a dog. Marinalla on pyörä. — Marina has a bike.

On never changes — it's always on, whoever the owner is. Minulla olen is a classic beginner's slip.