Text item will help you set a response in text form. Here you have an option of adding a button to the text.
The response while using the button can be invoked in form of a Flow, URL, or Buy now. Without setting them your action will remain incomplete.
When you select flow as your response, you will be able to direct the user to any particular flow that you have created.
Here you simply paste the URL of the page you wish to direct your users. You can add a feature by selecting URL inline. By selecting this feature, the link will open within the bot itself, when the user clicks on it.
This set of response is only available when you enable payment in your bot. Here the user can directly buy any product or service by clicking on buy button. How to enable payments is explained in the configure section in this document.