Is NISA still tax-free after 5 years?

I’m confused about the tax-free status of NISA accounts. I’m reading that your NISA is only tax-free the first five years of opening the account. Does this mean if I sell my stocks after 5 years, I will be liable to pay capital gains tax on my profit? If so, I don’t understand the merit of NISA as the general advice is to hold onto your stocks for at least five years. But perhaps I’m not understanding NISA rules correctly.