It's an old saying that breeders use which basically means, the type and shape of the bird should be your first priority when breeding to the standard of perfection. After the type is correct then you can work on colour. When many breeders start out they make the common mistake of trying to improve the colour of the bird first. This is because its the easiest to see what to improve on.
(I've made this mistake myself, and it took a good few years to fix it. I was working with pekin bantams and I had the cuckoo colour very good. But their type was very poor. So the only way to improve my birds was to use a black rooster to improve their shape. This messed up the colouring. So i had to start again with the cuckoo pattern. But this time I had better quaility birds.)
