This is the 3886th most frequent Russian word.
британская
"British" (adjective).
The word 'британская' is used here as an adjective describing 'кухню' (cuisine), indicating its origin.
Она любит британскую кухню.
She loves British cuisine.
In this case, 'британская' describes 'подруга' (friend), specifying her nationality.
Моя британская подруга прислала письмо.
My British friend sent a letter.
Here, 'британская' serves as an adjective modifying 'классика' (classic), suggesting that the classic belongs to the British cultural context.