In hobby speak, a "hit" is the good stuff — the higher-value chase cards that make ripping packs worth it. Autographs, relic cards, insert cards, and coveted rookie cards all fall under the hit umbrella.
Some products even guarantee a specific number of hits per box, so you know you're walking away with at least a few premium pulls. That guaranteed hit count is one of the key factors collectors weigh when deciding which products to buy. More guaranteed hits usually means a higher price point, but also a better shot at pulling something that makes the whole box worth it.