When you make a cake, particularly if you're following a banana loaf recipe, there are many different ways to combine the ingredients. One of the easiest baking methods to learn is known as the "rubbing-in method". You will see it written in recipe books as "now rub the fat into the flour" or "now combine the ingredients using the rubbing-in method". Quite simply, it is the technique of using your fingers to combine hard fat (butter, margarine or lard) and flour by rubbing them together.
You may already be familiar with the rubbing-in method if you have ever made home-made crumble for a fruit crumble pudding or home-made pastry - you may just not have known it had a name!