In this snippet, you can see how to add a vertical line in HTML. But you need to use CSS, as well. Add a vertical line on the left or right side by using the border-left or border-right properties, respectively. See also how to center a vertical line and how to add a vertical line before a text.
<!DOCTYPE html>
<html>
<head>
<title>Title of the document</title>
<style>
.verticalLine {
border-left: 4px solid #f24976;
height: 200px;
}
</style>
</head>
<body>
<div class="verticalLine"></div>
</body>
</html>