To summon means ‘to call a person to come to a place’. A summons is a law-paper from a court telling a person they must come to court or bring something to court (like documents). (From the Plain English Legal Dictionary 2015)
Talk to a lawyer about what will happen in court. If you do not go to court the police might arrest you. If you can’t get to court on the right date, talk to a lawyer or go to the court on an earlier date.