Labels can help you to mark the leads to create more visibility within your account.
To manage all labels:
go to the Account Settings
select the Settings tab on the left panel
and enable the Edit Label Settings toggle.
Once the toggle is enabled, you are able to:
add new labels (Input new label field);
edit/delete/set color of existing labels;
set default label (that will be applied to all incoming conversations).
To hide label settings, just disable the toggle. This action does not influence the function of the labels.