毎年沢山の数の書物が出版されている。

。

Every year, a great number of books are published.

Literal

Every-year plenty's number's books [subject-が] are-being-published.

沢山 ('plenty, lots') is a na-adjective/adverb for 'many.' 書物 ('books') is a formal/literary word, more elevated than the everyday 本. 出版される is the passive of 出版する ('to publish'), with ~ている marking the ongoing state: 'are published' as a current phenomenon.