Product / Category Title Pattern
You can leave this field empty or fill up something like this. If the field is left empty, the title that will be shown while sharing the page will be the product title / category title.
If fill up something like this,
will look like
Use a proper cover image, this image will be used as default image so when you share page like home page, this image will be shown.
Cover Image Size / Product Image Size / Category Image Size
These fields cannot be left empty and must have proper value. The values mentioned here will be used to resize your images accordingly