This is the 804th most frequent Polish word.
moje
"Moje" means "my" or "mine" in English.
In this sentence, 'moje' is a possessive adjective referring to the first-person singular possessive form in the nominative case, corresponding to the feminine plural noun 'koty' (cats).
Moje koty są bardzo przyjazne.
My cats are very friendly.
Here, 'moje' is in the accusative case as it describes the direct object 'książki' (books), which is plural and feminine in this instance.
Widzę moje książki na stole.
I see my books on the table.
In this usage, 'moje' serves as a possessive adjective in the nominative case, modifying the plural noun 'rzeczy' (things), indicating ownership by the speaker.