This is the 717th most frequent German word.
britische
"Britische" means "British" in English.
In this instance, 'britische' modifies the noun 'Literatur' (literature), which is feminine, singular, and in the accusative case due to its role as the object of the sentence.
Ich lese gerne britische Literatur aus dem 19. Jahrhundert.
I enjoy reading British literature from the 19th century.
Here, 'britische' is an adjective modifying the plural noun 'Münzen' (coins), agreeing in number and case (nominative plural) with the noun.
Das sind britische Münzen, die ich gesammelt habe.
These are British coins that I have collected.
Here, 'britische' is used as an adjective modifying the singular noun 'Kultur' (culture). It agrees in gender (feminine), number (singular), and case (nominative) with the noun it describes.