Minecraft wiki entry for Raw_JSON_text_format, associated text: The text component.
 score: Displays a score holder's current score in an objective. Displays nothing if the given score holder or the given objective do not exist, or if the score holder is not tracked in the objective.
 name: The name of the score holder whose score should be displayed. This can be a selector like @p or an explicit name. If the text is a selector, the selector must be guaranteed to never select more than one entity, possibly by adding limit=1. If the text is "*", it shows the reader's own score (for example, /tellraw @a {"score":{"name":"*","objective":"obj"}} shows every online player their own score in the "obj" objective).[note 4]
 objective: The internal name of the objective to display the player's score in.
 value: Optional. If present, this value is displayed regardless of what the score would have been.