"Show me white shirts."
Translation:Покажіть мені білі сорочки.
That would be the case if there was one shirt ("сорочка" --> "сорочку").
In plural however, only "living" objects get put into an accusative plural form. All the "unliving" objects stay in the nominative plural form.
That's why it is simply "сорочки", even though it indeed is the accusative case here.