「」。
The shuttlecocks struck in a hanetsuki paddle game are made from the seeds of a large tree called 'mukuroji.'
Literal
Hanetsuki-paddle [with-で] strike feather-ball [topic-は] 'mukuroji' [called-という] big-tree [genitive-の] seed is.
A factoid about a traditional New Year's game. 羽子板 (hagoita) is the wooden paddle used in hanetsuki, a traditional Japanese badminton-like game historically played around New Year's. 羽の玉 ('feather-ball') refers to the 羽根 (hane, shuttlecock) used in the game. The big-tree 'mukuroji' (無患子, Sapindus mukorossi) is a species whose hard black seeds are traditionally used as the core of the shuttlecock. ~という is the 'called X' construction introducing a name. The whole sentence is a chain of information: the thing you hit → with a certain paddle → is the seed → of a tree → called mukuroji.