Everyman is a Medieval morality play, written in obvious allegory. Each of the characters has a name which represents the quality they have (for example, Beauty is concerned about outward appearance). Allegory makes it easy to understand each character's role in the story.
In this play, the main character is Everyman--someone who literally represents each of us. God sends Death to get Everyman; Everyman tells Death he is not prepared to face God and give his final accounting, as would probably be true of most of us. Everyman asks for more time and he asks to bring some friends along; he gets both requests but must set out on his journey to meet God. All the "friends" he thought he had are not interested in the journey or the destination. Among others, Beauty leaves him, Five-Wits (his five senses) leaves him...none of them are willing or able to accompany Everyman to the next life.
The only person (the only thing) Everyman finds to take with him is Good Deeds. This is the principle taught by the Medieval Church--you must do good deeds (good works) while you're living in order to find favor in the next world (heaven). The theme of the play is dramatized by the use of allegory, as it's difficult to miss the point when the names and character traits are so obvious.
Hope that helps!