The entity generation token adjustment (or Boost score) is a collection of factors attached to an Entity Generation that can apply additional ranking weight to tokens that match the search query.
Thgey are stored in the entity_generation_token_adjustment table.
This is done so that pages that contain the searched for keyword in their title, URL or other important metadata rank above pages that simply contain those words in their text. The idea being that words are significantly more relevant when they also appear in the title.
Correctly applied the product of all relevant factor fields is multiplied onto the final score, but since there is no fitting aggregation function the formula SUM(factor)-COUNT(*)+1 is used as a workaround. This means that factors smaller than 1.0 will result in unexpected behaviour.