This is the 9209th most frequent Japanese word.
玉川
"Tamagawa" (玉川) means "Jewel River" or "Precious Stone River."
In this sentence, '玉川' refers to the geographical name of a specific river in Japan.
玉川は東京を流れる川です。
Tamagawa is a river flowing through Tokyo.
Here, '玉川' is used to indicate the location where the person enjoys fishing.
彼は玉川で魚を釣るのが好きです。
He likes fishing at the Tamagawa River.
In this context, '玉川' signifies the place where the cherry blossom trees are located.