Create buttons without words

How can I create a button without words - icon only? When I don't add a title for the button the button doesn't appear on the touchbar.

Select the top-level trigger, then on the right look immediately underneath the icon selector.

Tick the box marked "Show only icon, no text." This does tend to make the buttons very small, so you may want to use the icon width and height controls underneath to embiggen things a bit.

Here the screenshot illustrating the correct explanation above.