It is, I think, for women, ejaculation is just like for men, a sign of intense sexual pleasure. You're very right also that it can occur at any point during sexual response, not just at orgasm, but before, during, or even after. It's perfectly normal. We have two related questions. First of all, let me preface this by saying it is not essential to sexual pleasure.
People can have marvelous sex and never have an orgasm.
The second part is that I think there are different kinds of orgasms. I think all orgasms are clitoral. That is, the clitoral system is the mechanism by which you get the spasms. Many women say they feel spasms or a contracting of muscles in the pelvic floor. Other women say they feel like a warm glow that spreads from the genitals down the thighs and to the knees or feet sometimes and upward to the heart or the brain even.