Usually, only one egg is released by a woman during ovulation. After its release, the egg moves to the fallopian tube, where it stays for about twelve to twenty-four hours. During this time, a woman can conceive if the egg is fertilized by a sperm. The fertilized egg then moves out of the fallopian tubes and implants itself in the uterus within six to ten days. However, if the egg is not fertilized, it dissolves and is passed out of the woman’s body as menstrual flow.
Sometimes, more than one egg is released during ovulation, a concept called multiple ovulation. When, for instance, two eggs are released and each one is fertilized, the woman has fraternal twins. According to the American Pregnancy Association, multiple ovulation happens in about five to ten percent of all cycles but does not readily yield as many fraternal twins because of another concept that is called “the vanishing twin phenomenon.” The vanishing twin phenomenon states that “a twin or multiple can disappear in the uterus during pregnancy, due to miscarriage.” When this happens, the lost fetal tissue is taken up by “the twin, multiple, placenta or the mother.”
I assume you are referring to human females. A female releases only 1 egg per cycle of 28 days or so.
The female body over its lifetime develops a certain number of eggs. These are released one at a time during the mensturation cycle, every 28 days or so. In all, a healthy female body will release these eggs over a period of 30 or so years. In exceptional cases, 2 eggs may be released at one cycle, that is how twins are born.
During each cycle, one egg is released from the ovaries. It waits in the Fallopian tubes for fertilization by a sperm. If it is not fertilized, it is removed along with menstrual fluids.
Just a fun fact, unlike men who can produce sperm everyday, females are born with all the eggs (follicles) they will ever release.