A more thorough explanation:

A note of hand is a type of promissory note. It is a written promise to pay a certain amount of money to a person or entity at a specific time in the future. Plural of note of hand is notes of hand.

John borrowed $500 from his friend and gave him a note of hand promising to pay back the amount with interest in six months.

Another example could be a business owner giving a note of hand to a supplier, promising to pay for goods received within 30 days.

These examples illustrate how a note of hand is a written promise to pay a specific amount of money at a specific time in the future.