This is the 7202nd most frequent Polish word.
jaroszyńskim
"Jaroszyńskim" is the instrumental form of the adjective derived from "Jaroszyński," which typically refers to something or someone associated with the surname Jaroszyński.
In this sentence, "Jaroszyńskim" refers to a person, expressed in the instrumental case due to its role as the object of 'rozmawiać z' (to talk with).
Wczoraj rozmawialiśmy z Jaroszyńskim o jego nowym projekcie.
Yesterday, we talked with Jaroszyński about his new project.
Here, "Jaroszyńskiego" is used in the genitive case, indicating possession or authorship attributed to Jaroszyński.
Dzieła napisane przez Jaroszyńskiego są bardzo inspirujące.
Works written by Jaroszyński are very inspiring.
In this case, "Jaroszyńskiego" denotes the name of the street, used in the genitive case to express location.