Nikhil Narale
Ansys Employee

It looks like you have assigned the Named Selections but haven't updated the Mesh and the Fluent tasks in the workbench workflow. Try doing the following:
1: After assigning Named Selection, update the mesh task.
2: If the Fluent is opened, you will notice a green refresh button at the top left of the Fluent window. Click on it to refresh. Now you can the see the labels, that you have defined, in the boundary conditions.

I hope this helps.