A more thorough explanation:

NOTA BENE

Nota bene is a Latin phrase that means "note well" or "take notice". It is often abbreviated as N.B. and used to draw attention to important information in a text.

• N.B. Please remember to bring your ID to the exam tomorrow.
• N.B. This offer is only valid until the end of the month.

In both examples, the abbreviation N.B. is used to highlight important information that the reader should pay attention to. The first example reminds the reader to bring their ID to the exam, while the second example indicates that the offer has a limited time frame.