To access Item Variant Details go to:

Stock > Item Variant Details Under other reports

An Item Variant is a version of an Item with different attributes like sizes or colors.

Eg: Suppose t-shirt is an Item and it comes in different sizes and colors like small, medium, large and red, blue, green. In ERPNext the t-shirt will be considered as an Item template and each of the variations will be an Item Variant.

A blue t-shirt in size small rather than just a t-shirt. Item variants let you treat the small, medium, and large versions of a t-shirt as variations of one Item 't-shirt'.

Item Variant Details shows all details related ao an item variant