When you are working with Excel Linked Tables as data sources for PowerPivot, you may notice that the name you labelled the table name (in Excel) has not imported into the PowerPivot data model as you expected. Instead you might see the name “Tablexx” where xx is a number rather than the custom name you gave the table back in Excel. Whilst you can rename the Table within the PowerPivot model, “Tablexx” still gets pumped back out when you browse the PowerPivot model in a Pivot Table or Chart.
As a workaround, delete the table from the PowerPivot model, then in Excel, go to Formulas, then Name Manager.
Within Name Manager you can then Filter to Tables, remove any duplicate references, then rename the name “Tablexx” to a custom name. Now when you add back into the PowerPivot data model this time, the custom name will come across and display correctly when you browse the model in a Pivot table or chart.
If you want to read more about Table naming in Excel, there is a fabulous read here