The Material Safety Data Sheet (MSDS) is a document that contains information on products with potential hazards. Many products, especially electronics, contain compounds that pose a health, fire, reactivity or environmental risks when shipped. An MSDS is usually required for lithium-ion batteries or products containing specified chemicals.
You can find an MSDS form by searching Google (or any other search engine) with the item name, model number and MSDS. For example, if you need an MSDS for an iPhone 7, use the search term "iphone 7 MSDS"" and you will see the link from Apple for the iPhone 7 MSDS. Download this document (typically a PDF) and upload it using the "Additional Documents" screen.