Jaishankar,
When you read a column from an Excel spreadsheet you simply use the following syntax: {{columnName}}. For example, if you have a column name called "FirstName" in your spreadsheet, then the property/variable syntax is: {{FirstName}}
Note that capitalization matters. Now if you have an XML somewhere, let's say you have the following XML:
<Employee>
<Name>Fred</Name>
</Employee>
And you want to parameterize the <Name> element then you can simply replace "Fred" with {{FirstName}} like this:
<Employee>
<Name>{{FirstName}}</Name>
</Employee>