Answer:
Cooking can be done with more variance in measurements, a pinch of this or a dash of that. Baking requires more precision. Think of it like a chemistry experiment. When baking, if there is too little of one thing or too much of another, one can get hockey puck type scones or a cake that collapses.
You need proper measuring tools like cups and measuring spoons (try the dollar store) or a kitchen scale and spoons. I know that in some countries recipes use weights like grams instead of volume like cups. If you get a comprehensive cookbook, it should explain how to measure.
Using the measuring tools correctly matters as well. For example, you should not pack flour down into the measuring cup, but to measure brown sugar you should pack it down.
