what is the function of grape seeds and how many types of grapes?

Answer 1

Grape seeds exist for the same reason seeds exist in all flowering plants: to propagate the species. However, since ancient times, grape vines in agriculture have often been propagated by grafting rather than by sexual reproduction (seeds). This allows for the specific characteristics of a variety of grape to be maintained with the risk of loss or mixing of genetic coding by outbreeding. Also, many cultivated varieties, if grown from seed have weak or inadequate rootstocks. Grafting onto wild grape rootstocks allows for a much more hardy and productive vine. In the wild, of course, grapes propagate by seed.

There are dozens, perhaps hundreds, or grape varieties. These include table grapes, drying (raisin) grapes, and wine grapes.
See the link below for a list: