There are a few different ways that people can interpret the term frigid. In general, it is used to describe someone who is uninterested in sex or has a low libido. It can also be used to describe someone who is uncomfortable with sexual activity, even if they do want to participate. In either case, it usually comes down to a lack of sexual desire or interest.
For some people, frigidity is simply a matter of personal preference. They may enjoy sex but don't feel the need to do it on a regular basis. Others may have medical conditions that affect their libido or ability to become aroused. And still others may have experienced trauma that has led them to avoid sexual activity altogether.
Whatever the reason, there's nothing wrong with being frigid. It's perfectly normal and there's no shame in it. If you're not interested in sex, that's OK! You can still lead a happy and fulfilling life without ever having intercourse.