This is the 287th most frequent Finnish word.
antti
"Antti" is a Finnish male given name.
In this sentence, "Antti" serves as a proper noun, identifying a person named Antti as the subject of the action.
Antti on menossa kauppaan.
Antti is going to the store.
In this instance, "Antin" also uses the genitive form to indicate possession, specifying that the house belongs to Antti.
Tämä on Antin talo.
This is Antti's house.
Here, "Antin" is the genitive form of the noun "Antti," showing possession or a relational connection to another word, in this case, indicating whom the conversation is with.