The Text Field mode is used to add text fields to documents. Text fields are used to denote a space in which users can can enter text, such as their address, or credit card details. Date fields are a custom Text field that prompt the user for a date when clicked. See here for further information.
Once you have placed a text field, you can Customize the format by giving it a background color, changing the text color, and more. All of these options are available in the Format tab, on the right of the ribbon:
After you have customized the field to your liking, you can simply go back to the Hand tool to begin filling the field or send it to a Client to fill in.