This is the 682nd most frequent German word.
europäische
"Europäische" means "European."
In this sentence, 'europäische' serves as an adjective modifying the noun 'Kultur' (culture), describing it as pertaining to Europe.
Die europäische Kultur hat eine reiche Geschichte.
The European culture has a rich history.
Here, 'europäische' functions as an adjective describing 'Länder' (countries), indicating they are part of Europe.
Einige europäische Länder sind für ihre Architektur bekannt.
Some European countries are known for their architecture.
In this context, 'europäische' describes 'Union' (Union) as referencing the European entity.