What does "Hero" and other image sizes mean?

Image sizes reflect where the image is likely to be encountered by the consumer. 

HERO IMAGE

The Hero Image size is the primary image for a product and is what the customer will first see when scrolling through a search results page.

SUPPLEMENTARY IMAGE

A supplementary image is only viewed when the consumer has already clicked through to the product page, so doesn't require details to be as clear and comprehensible.

STANDARD PHONE

Scores the image as if the consumer was viewing it on a standard phone screen (between 6.1-6.5 inches).

PLUS/MAX PHONE

Scores the image as if the consumer was viewing it on a plus/max phone screen (approx 6.7 inches).

META AD TEMPLATE

Scores the imageas if the consumer were to view it within the Meta ad ecosystem:

Ratio: 1.91:1 to 4:5 

Resolution:

-1:1 ratio: 1440 x 1440 pixels

-4:5 ratio: 1440 x 1800 pixels