To add a label to announcement bar, like this.
You can also use this free tool to create announcement bar, so you can add label easier without using custom code.
#1. First, highlight text in Announcement Bar > Choose Underline
#2. Next, use this code to Custom CSS
div#announcement-bar-text-inner-id p u {
text-decoration: none !important;
background-color: red;
padding: 5px 10px;
border-radius: 30px;
display: inline-block;
font-size: 13px;
}