$ComponentLabel
A global merge field to use when referencing the label of an inputField component on a Visualforce page that is associated with
a message.
Usage
Return the label of an inputField component that is associated with a message.
Example
<apex:datalist var="mess" value="{!messages}">
<apex:outputText value="{!mess.componentLabel}:" style="color:red"/>
<apex:outputText value="{!mess.detail}" style="color:black" />
</apex:datalist>