Knorr and Maggi are the leading brands here,though the 'own' brands of Coop and Migros are also ok and palatable

The stock cubes ( called rinds bouillon de boeuf/ or hühner bouillon de poule) are usually stocked in the aisles with the other condiments such as salt and pepper and the ready made sauces and soups and stuff like that.
You can get it in cubes or in granulated form.
If you want to push the boat out and make a light soup with some cut up veggies floating in it then buy FOND de boeuf or Fond de Poule