Index/ Counter in the Visual force using Apex:Variable.
The requirement where index along with the each record repeated in the "apex:repeat" tag. The following snippet will be helpful.
<apex:variable value="0" var="index" />
<apex:repeat value="{!contacts}" var="contact">
<apex:variable var="index" value="{!VALUE(index) + 1}"/>
{!index} . {!contact.Name}
</apex:repeat>
<apex:variable value="0" var="index" />
Create a variable of name "index" & initialize it to "0"
<apex:variable var="index" value="{!VALUE(index) + 1}"/>
Inside the loop increment the index value.
{!index}
Use the index variable as above, where ever needed.
Happy Coding