Bonjour Geeforce,
Under the samples there is a section called Area Transformation. There are scaling properties there. If you change them, you'll see the area changing accordingly in the viewports.
The samples is the "definition" of the area light. Low values result in grainy shadows, but render fast; high values result in smooth shadows, but takes much longer to render.
Hope this helps
Salutations - Cheers
Bernard Lebel