NRML under the Equity segment is an investment product, where you only have to pay a certain percentage of the total amount upfront using cash or pledged shares. You can settle the balance amount within the next two trading days by depositing funds or pledging shares for more margin.
Let us understand with an example: You want to buy 100 shares of ITC at Rs. 200 each. Total amount = Rs. 20000
Consider the margin requirement for ITC using Prime is 20% i.e Rs.4000. You will have to pay Rs. 4000 upfront using cash or margin against your pledged shares. While the balance amount i.e Rs. 16000 has to be paid within the next two trading days. This should be done by simply adding funds to your trading account in form of cash, or pledging shares for more margin. Your shares would be squared off in case you fail to make the payment before the due date.