This feature is not available in Squid for Android at this time.
Labels are a way of organizing your notes so that they become easily located when a particular label (or multiple labels) are searched. To give a note a label, first bring up the app bar menu by swiping from the bottom of the screen (Windows) or by tapping the three dots in the lower right corner (Windows Phone), then tap Labels. You can add a new label to apply to the note, or select from existing labels. Once you have applied a label(s), tap Done (checkmark icon).
To show all notes with a particular label(s), go to the Squid main screen (landing page), and tap Search (magnifying glass icon). Then select the label(s) you want to see. Any note with the searched label(s) will be displayed.