Being a female puts you at greater risk for osteoporosis. Getting enough calcium and vitamin D in the diet is not only important for bone health but also things like blood clotting and nerve/muscle function.
Calcium consumption needs vitamin D to be absorbed properly, without vitamin D, your calcium could be going to waste. Sunlight is usually the main form of vitamin D for many people. If sun exposure isn’t a guarantee for you or the risks of sun exposure worry you, you can get vitamin D elsewhere.