毎月

毎月

"Every month."

In this sentence, 毎月 indicates a recurring event (purchasing a book) that happens on a monthly basis.

私は毎月新しい本を購入しています。

I purchase a new book every month.

Here, 毎月 specifies a regular obligation (rent payment) occurring at the end of each monthly cycle.

家賃は毎月の終わりに支払います。

The rent is paid at the end of every month.

In this example, 毎月 establishes the periodicity (once) over the span of a month, emphasizing the single recurring action.

健康のために毎月一回ジムに行っています。

For health reasons, I go to the gym once a month.