Information gain is the new, useful information a page adds beyond what the pages already ranking for its query say. A search engine has little reason to show an eleventh version of the same ten answers, so a page that only restates the consensus competes on authority alone, which a growing site rarely has enough of.
Information gain usually comes from what only the business knows: how its own pricing works, its process, its measurements, the questions its staff hear every week and the mistakes customers make. For a jewelry store, that might be how a particular setting style affects how often stones need checking. For a storage facility, it might be which unit sizes customers moving out of a one-bedroom apartment actually rent, rather than the generic chart every competitor copies.
The facts themselves should be written as clean EAV statements: the entity named, the attribute explicit, the value precise. “Our 10×20 units hold the contents of a typical three-bedroom house” is a fact a search engine can store and a reader can act on. “We have plenty of spacious options” is neither. Answer-first sentences, specific values and one claim per sentence make a page easy to understand, easy to quote and easy to verify, and they’re the standard behind my semantic content writing.