Net effective rent is a calculation of average monthly rental cost that incorporates landlord rental concessions, typically a free month of rent. For example, if an apartment was being advertised with a net effective rent of $1500/month for a 12-month lease with one month of free rent, it might actually have a monthly rent of $1625. However, if you take the entire rent paid over the 13-month period, it actually has an average, or “net effective” rent of $1500/month.
Net present value, or NPV, is a financial metric that can help commercial real estate investors determine whether they're getting a certain return-- a 'target yield,' given the amount of their initial investment. Using the NPV equation, you can take a building's current net cash flows and your required rate of return, and determine what a building's value is to you, the investor, right now.