The CSAT(Customer satisfaction score) generally represents how happy customers are with your product or service or specific experience. CSAT is one of the critical customer satisfaction metrics in OMNI that any customer-facing business should monitor. When an agent resolves the conversation, OMNI sends a survey to your customers for rating and feedback. It's calculated by asking a question, such as "Rate your conversation" There's a corresponding survey emoji scale. After submitting the rating, the customer can give more feedback which is optional.
Shown below from FB Messenger.
To enable/disable CSAT, navigate to the inbox settings (CSAT is disabled default)