I got it!
I had to prepare the input txt file with the two columns (name and number) separed by a TAB.
In scribus create a new text frame and load the above textfile.
Select the above text frame.
Then near Colums and Text Distance select the "Tabulators button":
https://wiki.scribus.net/canvas/Working_with_text_frames#Properties:_Shape_TabNow appears its poup up and it is possible to set a tabultaor just by clicking on the "ruler bar"...
And select filling character > dot or something similar, I have the italian version and I can read: "Carattere di riempimento", then I select "punto" (it should be point or dot in english).
Finally by pressing "OK" the result will be shown and applied, with few tries it became clear how it works.
So finally I solved.
Anyway I think it'is not explained enough how this "Tabulators" tool really works. A bit more detailed guide in the wiki would be greatly appreciated!

Bye