Chat actions allow you to send a message to the channel's chat.
This message will be sent from your custom Bot account if one is signed in, otherwise it will send from your Streamer account. You can click on the Send as Streamer option to force the message to be sent from the Streamer's account.
If your streaming platform supports whispers or private messages, you can toggle the Whisper option to send the message as one. This will be sent to the user who ran the command or you can specify a user to optionally send it to.
Whispers not sending on Twitch? Check out the whisper limitations set by Twitch: https://dev.twitch.tv/docs/chat/whispers/
You may use Special Identifiers in the chat message text & the whisper user.