Female ejaculation is the emission of liquid from a woman during orgasm. It is inherent in orgasm that the vagina becomes lubricated with mucus so that the woman becomes damp; biologically, this is to facilitate the entry of a penis. Often, a small amount of a whitish fluid will ooze out.
However, the "gushing" or "squirting" of a significant amount of liquid sometimes depicted in pornography has a different cause. In many cases, it is mostly urine expelled from the bladder. The expulsion may be due to a conscious effort by the woman rather than a spontaneous act. However, there may also be prostate-specific androgen originating from the Skene’s glands. Some people imagine that gushing is an essential part of a good orgasm, but this seems to be false and many women rarely or never gush.
Ejaculation seem often to be associated with stimulation of the G-spot, since there are reports of it occurring (and surprising) for the first time when this is done. Since the G-spot is hard to find in many women, and the process requires some getting used to (reports are that it feels like having to pee), this is usually not automatic.