The Label property represents the actual text that appears as a control's label. To create a label simply fill in the textbox next to the property.

Adding a 'Temperature' Label to a slider control
A 'Temperature' Label on a slider control

Alternatively, you can also click the button next to the Label property and then enter the Label name into the Enter Text Dialog. This also gives you easy access to the HTML editor.

The Enter Text dialog
A 'Temperature' Label on a QR control