Must be a plain text. Can include spaces as well as target selectors. The game replaces entity selectors in the message with the list of selected entities' names, which is formatted as "name1 and name2" for two entities, or "name1, name2, ... and namen" for n entities. In Bedrock Edition, @here can be used to mention all players.
the arguments are not specified correctly
<targets> or player: target fails to resolve to one or more online players