That's a good question. Staminate flowers do indeed only have male reproductive organs. However, they can occur simultaneously on plants with pistillate flowers, which are their female counterpart. Examples of such plants are squash, corn, and begonias.

Alternatively, some species have the staminate and pistillate flowers on different plants. Examples include asparagus, spinach and cottonwood. Regardless of whether they occur on the same plant or on different plants, the flowers are in close enough proximity that fertilization can occur.

They don't make seeds. They make pollen. The pollen gets transported to the female stigma of another flower, which fertilizes it, allowing the carpellate (female) flower to make a fruit with seeds.

Staminate flowers are one of the reasons why plants are so cool. They have so many different ways in which they reproduce! Just like humans which have males and females, some plant species have male and female plants instead of having flowers with both male and female parts (the norm). Plants with only male reproductive organs transfer pollen to a pollinator or through wind to another plant of the same species with female flowers. The female flowers are pollinated and produce seeds using the pollen produced from the male flowers!