This is the 7626th most frequent Polish word.
leszek
"Leszek" is a Polish masculine given name.
Used here as a proper noun, referring to a person's name in Polish.
Leszek mieszka w Warszawie.
Leszek lives in Warsaw.
Again, 'Leszek' is used as a person's name, to identify the subject of the question personally.
Czy Leszek już wrócił z podróży?
Has Leszek returned from his trip yet?
Here 'Leszek' is the title of a creative work, likely referring to a concept or symbolic representation associated with the name.