This is the 6069th most frequent Polish word.
aleksieja
"Aleksieja" is not a standard Polish word; it might be a name or misspelling.
Here, 'Aleksieja' functions as the genitive case of the proper noun Aleksiej, showing ownership or connection.
Aleksieja był bardzo zadowolony ze swojego nowego odkrycia.
Aleksieja was very satisfied with his new discovery.
In this sentence, 'Aleksieja' denotes possession, identifying the book as belonging to Aleksiej.
Przeczytałem książkę Aleksieja, którą mi polecił.
I read Aleksieja's book, which he recommended to me.
In this case, 'Aleksieja' is used in the accusative case, indicating the object of action related to Aleksiej.