I would like to know what "for each flat" means in the following sentences:
I had known him almost all my life, Beniek. He lived around the corner from us, in our neighbourhood in Wrocław, composed of rounded streets and three-storey apartment buildings that from the air formed a giant eagle, the symbol of our nation. There were hedges and wide courtyards with a little garden for each flat, and cool, damp cellars and dusty attics. It hadn’t even been twenty years since any of our families had come to live there. Our postboxes still said ‘Briefe’ in German. Everyone – the people who’d lived here before and the people who replaced them – had been forced to leave their home. From one day to the next, the continent’s borders had shifted, redrawn like the chalk lines of the hopscotch we played on the pavement. At the end of the war, the east of Germany became Poland and the east of Poland became the Soviet Union. Granny’s family were forced to leave their land near Lwów. The Soviets took their house and hauled them on the same cattle trains that had brought the Jews to the camps a year or two earlier. They ended up in Wrocław, a city inhabited by the Germans for hundreds of years, in a flat only just deserted by some family we’d never know, their dishes still in the sink, their breadcrumbs on the table. This is where I grew up.
In this novel which is set in the 1980's in Poland under the socialist regime, where homosexuality was socially unacceptable, the protagonist Ludwik (a university graduate) left Poland in 1981 to live in the United States of America. And he remembers what it was like back then in Poland, where he used to hang out with his friends including his first love Beniek in his hometown of Wrocław when he was nine years old.
In this part, I wonder whether the "flat" here means each storey in an apartment building, or an apartment building itself. I am confused because the sentence has a description saying that "each flat" had "hedges, wide courtyards with a garden, and cellars and dusty attics." So I thought, how can a single one-storied "flat" can have hedges and gardens and cellars and attics? So I wanted to ask you.
I am an English learner from South Korea. I would very much appreciate your help. :)