egg
The Italian word for egg is 'uovo'. This is a singular noun and its plural is 'uova'. For example, if you want to say scrambled eggs, you would say 'uova strapazzate'.
I ate an egg for breakfast.
This sentence is used to inform someone about what you had for breakfast. The word 'uovo' here is used in the context of food.
The rooster does not lay eggs.
It is a common phrase used to state an obvious fact in a humorous or ironic way, as it is widely known that roosters, being males, do not lay eggs. Here, 'uovo' means 'egg'.
This painting is worth an egg without salt.
This is an idiomatic expression. Eggs without salt are tasteless and not very valuable, so the painting is not worth much. In this context, 'uovo' is part of an Italian idiomatic simile.