Search in the Documentation:

Skin rendering

Unlike other elements, the skin is not rendered by Jahia the same way, but instead wraps a content object. Because of this, the ${currentNode} expression does not reference the skin but the skinned object. The output of the wrapped node is also available through the ${wrappedContent} expression.

Example of a skin using the title of the skinned object

<jcr:nodeProperty node="${currentNode}" name="jcr:title" var="title"/>
<div class="skin">
<c:if test="${not empty title}">
<h3 class="title">${fn:escapeXml(title.string)}</h3>
</c:if>
${wrappedContent}
<div class="clear"></div>
</div>