Something that is difficult to do.
This idiom means that something is not easy and requires effort, skill, or patience to accomplish.
No, this-- no it is not a piece of cake at all.
No, esto... no, no es pan comido en absoluto.
This is not a piece of cake degree.
Este grado no es pan comido.
This is not a piece of cake.
Esto no es pan comido.
The IELTS exam is not a piece of cake.
El examen IELTS no es pan comido.
However, being a plus size model is not a piece of cake.
Sin embargo, ser modelo de talla grande no es pan comido.