Smart Bulk Resolutions groups missing required fields by category — set one value, click Apply, and every affected product updates at once.
When a whole category of products is missing the same required field — every t-shirt missing brand, every mug missing material — you don't fix them one by one. The Smart Bulk Resolutions button in the Inventory page header (it shows how many products it can resolve, and hides itself at zero) opens a side panel that groups the gaps for you. It works over the products your search chips select — one marketplace, or all of them.
eBay's business policies get a special card labelled All categories — payment, return and fulfillment policies belong to the eBay connection, not to a category, so one dropdown choice applies to every category of that marketplace at once.
A second kind of card appears when a marketplace refused to publish products because of their category: pick a better category in the card and press Move, and every product in that group moves, with its required fields recalculated. When your list spans more than one marketplace, each card names the marketplace it belongs to.
Tell us what you were doing and what happened — the notification text or a product SKU helps us find it fast.