Is it a condition for the sacrificial animal to reach a certain age, and what is meant by His saying, the Almighty: "what can be obtained easily of the sacrificial animals"?

"What suffices from sheep is that which has completed six months, and from goats that which has completed one year, and from cattle that which has completed two years, and from camels that which has completed five years. Anything less than that does not suffice as a sacrificial animal (hady) or an animal for Eid al-Adha (udhiyah)."