This is the 6356th most frequent Polish word.
brzóza
"Brzóza" in Polish means "birch tree" in English.
The word 'brzoza' is used here as a noun in its basic form, meaning a birch tree.
Widzę piękną brzozę w ogrodzie.
I see a beautiful birch tree in the garden.
The word 'brzozy' is in the possessive form (genitive singular), referring to the leaves 'of the birch tree'.
Jesienią liście brzozy są złociste.
In autumn, the leaves of the birch tree are golden.
Here, 'brzozy' is the plural form accusative case, indicating multiple birch trees being planted.