This is the 1348th most frequent Polish word.
polscy
"Polscy" means "Polish" (masculine personal plural form).
In this sentence, 'polscy' is an adjective that agrees in gender and number with the plural masculine noun 'sportowcy' (athletes), serving to specify that these athletes are Polish.
Polscy sportowcy zdobyli złoty medal.
Polish athletes won the gold medal.
Here, 'polscy' again functions as an adjective modifying the plural masculine noun 'naukowcy' (scientists), describing their Polish nationality.
Polscy naukowcy są znani na całym świecie za swoje odkrycia.
Polish scientists are known worldwide for their discoveries.
Once more, 'polscy' acts as an adjective qualifying the plural masculine noun 'pisarze' (writers), indicating their origin or association with Poland.