The proverb meglio un uovo oggi che una gallina domani literally means that it is better to have an egg today than a chicken tomorrow. This obviously indicates that it is better to have a sure thing in the present than expect a better outcome in the future that might not come about. It's the equivalent of "a bird in the hand is worth two in the bush."
Obviously the Italians never paid much attention to this proverb or else they would have consumed all the eggs before they hatched and chickens would have become extinct, taking all future eggs with them. No frittata. No pollo al mattone. Che disastro.
For my little compilation of Italian food expressions, see here.