Net 10, net 30, and net 60 mean you pay 10, 30, or 60 days after the invoice. Set your own payment terms first to protect your cash flow, then negotiate from there. If a client forces a standard term, work within it but push for the best timing you can get.
Some companies have payment terms like net 10 or net 30 or net 60. That means they pay you in 10 days or 30 days or 60 days from the time you invoice them. Put your own terms in here and then you can negotiate this later. If the client says we pay all of our vendors net 30, no exception, then adjust it to net 30. But first start with something that's favorable for you, for your cash flow, and then negotiate from that point.
