This is the 7627th most frequent Polish word.
leszno
"Leszno" is a proper noun, referring to a city in western Poland.
In this sentence, 'Leszno' is used as a proper noun referring to the name of a city.
Leszno to piękne miasto w Wielkopolsce.
Leszno is a beautiful city in Greater Poland.
Here, 'Leszno' again acts as a proper noun, specifically the object of the verb 'visited'.
W zeszłym tygodniu odwiedziłem Leszno, aby zobaczyć jego zabytki.
Last week, I visited Leszno to see its historical sites.
In this instance, 'Leszno' serves as the subject of the sentence.