Praise be to Allah, and may peace and blessings be upon the Messenger of Allah.
Belief in the Last Day means firmly believing in everything that Allah تعالى has informed us of in His Book, and everything that His Messenger ﷺ has informed us about concerning what happens after death, and acting according to the implications of this belief.
This includes believing in the signs of the Hour, death and the states of the dying, the trial of the grave and its punishment and bliss, the blowing of the Trumpet, the resurrection, the horrors of the Day of Resurrection, the gathering and reckoning, Paradise and its bliss, and Hellfire and its punishment. Among the greatest blessings of the people of Paradise is seeing the Face of Allah تعالى, while among the most severe punishments of the people of Hell is being deprived of seeing their Lord, glorified and exalted.
When this belief becomes firmly established in the heart, it produces great benefits, including:
Desiring acts of obedience and being eager to perform them in hope of the reward of the Hereafter.
Avoiding sins and fearing Allah's punishment on the Day of Resurrection.
Being patient with what a believer misses of worldly pleasures, because of what he hopes for of the bliss and reward of the Hereafter.
Thus, belief in the Last Day is not merely an intellectual conviction; rather, it has a clear effect on a Muslim's words, deeds, and behavior.
We ask Allah تعالى to grant us sincere faith and firm certainty, and to make us among the people of His Paradise and His pleasure.
And Allah knows best.