本 + [noun]【běn】

本 in front of a noun means "this one here" or "our own": the organisation that is speaking, the place you are in, the period you are in. It is formal and belongs to notices, announcements, letters and official speech.

Our own organisation

A shop, company or school speaking about itself uses 本: 本店, 本公司, 本校. It replaces 我们, which would sound too casual on a sign.

The current one

With a time word, an event or a place, 本 means "the current": 本周, 本学期, 本次列车, 本市. 本人 is "I myself", the formal way to refer to yourself on a form or in a statement. 本文, "this paper", is a point of its own.

No 个, no 这

本 takes the noun directly, or a measure word of its own kind – 次, 届, 期. It never takes 个, and it does not stack with 这.

• × 本个月 → 本月
• × 这本公司 → 本公司

In 这本书 the 本 is the measure word for books, a different word. 本书 alone, in a preface, means "this book".

The formal word for "the one just mentioned" is 该: 该公司 is "the said company", someone else's, where 本公司 is your own.