To set a color label to a card, first open the Card Details and then click on Add colour tag located at the top of Card Description. Choose a color label from the drop-down list.
To change the text of a label, click on the Edit colour tags button at the bottom of the drop-down list. Then click on the necessary tag to change its text and then hit Enter on your keyboard. You can also remove text from the label and save it as empty.
Tip: Remove toggle from a checkbox opposite to color if you do not want to use this color on your dashboard. This color will not be displayed in the drop-down list within the Card Description.