Google has a list of attributes, known as product data specifications, which are used to format your product information in the Merchant Center. You can take a look at some of these attributes here.
Some attributes are required by Google and will lead to disapprovals if they’re not included. This is the case for specifications like price and shipping.
For attributes that aren’t compulsory, their removal could lead to a decrease in relevancy for Shopping ads. This could be the case if you removed the ‘brand’ attribute, for example, which could be very useful for search terms.