When a tutor has Suggested questions turned on, it offers three follow-ups after each answer. They give a student somewhere to go when they do not know what to ask next.
What they look like
The suggestions appear as bubbles under the reply. Clicking one sends it as the next message.
A student can ignore them entirely and type their own question.
Turning them on
Open the tutor, click Tutor settings, scroll to Suggested questions and turn the toggle on, then Save changes. See Using Suggested questions.