Dimensions are written as width by height. They decide how much detail an image can hold and whether a shopper can zoom into it: a product page enlarges the picture only when there are more pixels than the page shows at normal size. Dimensions are separate from the aspect ratio, which is the shape of the image, and from the file size, which is its weight.
A marketplace's minimum is the size below which an image is refused or shown without zoom; its recommended size is the one its pages are built around. Exporting at the recommended size is the safe choice. An image far above it gains nothing on the page and only makes the file heavier.
An image can be made smaller without visible loss, but not larger: enlarging spreads the same detail over more pixels. Upscaling rebuilds edges and texture more convincingly than plain enlargement, yet a blurred label stays unreadable. The dependable route to a large image is a sharp, close original.