This is the 3887th most frequent Polish word.
radosława
"Radosława" is a Polish feminine given name meaning "joy and glory" or "happy glory."
In this sentence, 'Radosława' is used as a proper noun, the name of a female person, and is the subject of the sentence.
Radosława była wesoła na przyjęciu.
Radosława was cheerful at the party.
Here, 'Radosławą' is the instrumental singular form of the proper noun Radosława, indicating interaction with her.
Spotkałem się z Radosławą.
I met with Radosława.
In this sentence, 'Radosławie' is used in the dative case, showing that the book was given to Radosława.