Minecraft /stats return types

General: If there's an entity selector (for example @p, @e, @r) in the command, it stores the amount of matched entities in AffectedEntities, otherwise AffectedEntities is set to 1

General: Stores the amount of entities, for which the command was successfully run, in SuccessCount

/testforblock, AffectedBlocks, either 0 or 1
/setblock, AffectedBlocks, 0 or 1

/scoreboard teams list, QueryResult, amount of teams
/scoreboard players list, QueryResult, amount of players tracked on any scoreboard
/scoreboard players list [playername], QueryResult, amount of scores for specified player
/scoreboard teams leave, AffectedEntities, amount of entities that left their team
/scoreboard teams join, AffectedEntities, amount of entities that joined a team
/scoreboard teams empty, AffectedEntities, amount of entities that were in the team

/list, QueryResult, amount of players in the world

/replaceitem, AffectedItems, amount of items in the new item stack

/xp, QueryResult, total XP or total XP levels, depending if relative or levels were added
/worldborder, QueryResult, the worldborder's diameter
/time query, QueryResult, the current daytime or gametime
/spreadplayers, AffectedEntities, the amount of entities that were spread
/give, AffectedItems, the amount of items given to the player
/gamerule, QueryResult, the gamerule's value as a number
/fill, AffectedBlocks, the amount of blocks that were filled
/enchant, AffectedItems, either 0 or 1
/testforblocks, AffectedBlocks, 0 or the amount of blocks that were matched
/clone, AffectedBlocks, the amount of blocks that were cloned
/clear, AffectedItems, the amount of items that were removed
/blockdata, AffectedBlocks, either 0 or 1