Variables are identifier for values sent to the ui objects from the server.

All objects that displays text can use variables, add them in your text and when you load your ui on the tablet or phone the variable key word will be exchanged with the correct value.

Example: Add the variable {system.cpu_total} in a label text field and when you load the ui it will display total cpu used on the windows pc.

Click the button next to the text field to bring up the text editor. There you find a button add variable, click on it to open the list over available variables to use.