Why was the 'Birth of Venus' made?

There are dozens of paintings of this subject made by various artists. When you ask about works of art you should always mention the name of the artist to make sure you get the correct answer. The most famous painting of this subject was made by Sandro Botticelli in Florence,

It was commissioned by a member of the wealthy Medici family.

All artists in the 15th and 16th centuries worked on commission only, and did not decide themselves what to paint.