The term '5 Net 7' on an invoice means that a 5% discount will be allowed on the price charged if payment is made within seven days. This is a common payment term used in business transactions. The number before the word 'Net' refers to the percentage of discount while the number after the word 'Net' indicates the number of days within which payment should be made to qualify for the discount. So, in this case, the buyer will receive a 5% discount if payment is made within 7 days from the invoice date.