A text balloon allows user to make a smaller, more targeted notation than a text box. The "point" on the balloon also allows the notation to be placed much more specifically than a text box.
In Style property dialog it is possible to change the text format and appearance of a balloon text container:
Allows you to change the text color and font size.
Text content of a ballon to be typed here.
Allows to change the background color and opacity level.
Sets the border color.
In Coordinates properties dialog you can set precisely the position of the balloon's point on the price scale (by setting the price) and the time axis (by setting the bar number):
In visibility properties dialog you can switch the Balloon tool displaying on charts of different timeframes: