This is the 1140th most frequent Japanese word.
世界一
"World's best" or "number one in the world."
Here, '世界一' is used to express 'the most in the world', indicating the highest comparison globally, linked to the adjective '美しい'.
富士山は世界一美しい山だと思います。
I think Mount Fuji is the most beautiful mountain in the world.
'世界一' emphasizes that the pasta is unique and unmatched globally in terms of taste.
このレストランのパスタは世界一おいしいです。
The pasta at this restaurant is the best in the world.
In this sentence, '世界一' expresses the peak capability in a global context, applied to the verb phrase '速く走る'.