Noobie question about SQL Query

Based on the screenshot, the query is auto generated, which is common. FYI, #(lf) .. line feed; 

#(tab) ... tab;

Before doing the changes, take a copy and work on it first, to get the solution

Option 1: Editing source in Applied Steps:

Select the query in Power Query Editor

Right side, you see the applied steps. Click the gear icon next to Source and see if you can change the query here.

Option 2: Code mode:

To add another simple column, edit the query in "power query editor" window using "Advanced Editor"...

change

        ,#(lf)#(tab)#(tab)m.nom_service,

as 

       ,#(lf)#(tab)#(tab)m.nom_service,,#(lf)#(tab)#(tab)t1.newcolname,

See if this works.

Hope this helps!