前略

手紙(てがみ)は「前略(ぜんりゃく)」で始(はじ)まった。

The letter began with "zenryaku," skipping the usual opening greetings.

前略(ぜんりゃく)、いかがお過(す)ごしでしょうか。

Dispensing with the preliminaries, how have you been?

引用文(いんようぶん)の前略(ぜんりゃく)は省略(しょうりゃく)された部分(ぶぶん)を示(しめ)す。

In a quoted passage, "zenryaku" marks the part that has been omitted at the beginning.

急(いそ)いでいたので、手紙(てがみ)の書(か)き出(だ)しは前略(ぜんりゃく)にした。

I was in a hurry, so I opened the letter with "zenryaku" instead of the formal greetings.