Feminized plants come from seeds that have been selectively bred to produce only female plants. Since female plants are the ones that produce flowers (which is where most of cannabis' cannabinoids are found), they are the only ones that are used to create marijuana products. Feminized seeds are intended to make things easier for growers by eliminating the need to determine the sex of growing plants and remove males early on to prevent fertilization. Generally, feminized seeds produce the same quality of plants as naturally produced seeds.
Flowering time refers to the time it takes for a plant to produce mature flowers. Cannabis flowering times are affected by the length of daily exposure the plant receives to sun (with the exception of the Cannabis ruderalis species, which flower automatically). When flowering times are reported for a strain, they are general estimates based on how the plants do on average in optimal conditions. Actual flowering times will vary and it is up to the grower to decide when to harvest for maximum benefit.
You probably know what flowers are; they're often the "pretty" part of a plant, and the same is true for cannabis. While cannabis flowers don't have traditional petals or look like daisies, they are still the reproductive organ of the female plants. Cannabis flowers are the hairy, sticky, crystal-covered bits that are harvested and dried to be used as medication. When they are allowed to be fertilized by male plants, these flowers will produce cannabis seeds. If not, they will continue to produce the resin that contains their active cannabinoids until they are harvested or begin to die.