To import products you have to:
1. create the categories (in the csv), if they don't already exists.
2. create the main product
3. create the variants.
Each variant type (color, size, ...) need a column.
You can find here an example of a csv ready to be imported. This csv contain a product without variants and one with variants.
On the right side of the csv, you can find the columns "color" and "size" (here for the example).
Before importing products with characteristics, you have to create the characteristics first in HikaShop.
Hope this will help you.