I have created one Context tag names as "Pump 1" and added its description as "Pump 1".

I need to create similar kind of 6 Pumps group all updates with description as "Pump 2", "Pump 3" and so on automatically.

How can I do that?

I suspect we might need a bit more detail on how you are adding these pumps or why it is difficult to name them on the initial setup, however, the following should answer the initial question.

Right-click in the description box and click the add a parameter expression. In the expression box. Enter \Name and the description will match the tag name. Click OK.