"Send messages" refers to sending information. Unlike Ask a question, Send messages simply sends a message without waiting for a user's reply or executing subsequent replies based on the user's response.
Types of Send Messages
Text
Messages in text format. Up to five can be sent consecutively at a time.
Text & URL Button
A combination of text and link in message format. The link can be placed in a button. Only one Text & URL Button message is supported per send.