Quick Text is a standard Salesforce Service Cloud Chat feature that allows agents to insert custom predefined messages into chats. You can read the SF KB article on setting up and using Quick Text here. 

When Quick Text is enabled, users see a new icon on the Unbabel chat component.

Unbabel added a quick text button from where the agent can paste a predefined template into the Unbabel Chat component directly.

Click on the Quick Text icon to open a new window where you can search and select a Quick Text message.

As soon as you select a Quick Text, it is applied to your message, and you can press enter to send it for translation.

Limitations

Quick text is not available for Messaging Sessions.