It's a Christian festival, maybe the second in importance to Christmas.
Christians remember the death and rising-to-heaven of Jesus Christ. There are important church services.
But for non-practicing Christians (me) it is a celebration of spring festival and in England that means sending friends and family an Easter card and giving them chocolate in the shape of eggs, rabbits, chicks, flowers...some people hold egg hunts for children.
The Easter Bunny (rabbit) is a popular character.
In Japan it is not a popular festival, so usually I don't do anything. BUt this year UK friends have sent me Easter chocolates. And I am eating...and eating...