When you add inputs to your web screens or web blocks to gather data from the end-users of the application you should add a caption describing the information that is being requested from the end user. The label widget provides this functionality.
One thing both Label and Text widgets have in common is that they serve perfectly well as captions for the inputs. The Label widget, however, provides usability and accessibility improvements over the Text widget.
The Label widget is bound to an input and by clicking on the label's text it activates that input. This is particularly relevant to improve accessibility of your forms because of the following:
Label Widget Properties | Gather Data in Web Screens