In Product overview > Click Short Description
From your Shopify admin, go to Settings -> Custom data
Click Products → Add Definition.
Please enter correct Namespace and Key as we noted below.
From your Shopify admin, go to Products -> All products.
Find and choose the product that you want to edit.
In the Metafields, please insert content for "Short Description" field.
Or you can access link 'Enter content for each product here.' => You can enter short description for each product