The <x:out> tag in JSTL (JavaServer Pages Standard Tag Library) is used to output XML data in a safe and escaped manner. Here's an example of how to use it:

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ taglib uri="http://java.sun.com/jsp/jstl/xml" prefix="x" %>

<x:parse var="myXml">
  <root>
    <item id="1">Item &lt;b&gt;1&lt;/b&gt;</item>
    <item id="2">Item &lt;i&gt;2&lt;/i&gt;</item>
    <item id="3">Item 3</item>
  </root>
</x:parse>


<x:forEach select="$myXml/root/item" var="item">
    - <x:out select="$item"/>

  </x:forEach>

In this example, we use the <x:parse> tag to parse an XML document into an object named myXml. We then use the <x:forEach> tag to iterate over the item elements in the XML document.

Within the <x:forEach> tag, we use the <x:out> tag to output the text content of the current item element in a safe and escaped manner. The select attribute is used to specify an XPath expression that selects the current item element.

Note that the <x:out> tag automatically escapes special characters such as <, >, and & to prevent them from being interpreted as HTML or XML tags. This helps to prevent cross-site scripting (XSS) attacks and other security vulnerabilities.