The feast of Saints Peter and Paul is observed on the June 29 in the Catholic church. However, in Sweden it is celebrated on the fourth Sunday of the common time. This is the time from Trinity Sunday until All Saints Sunday. The fourth Sunday of the common time frequently comes in July,
The liturgical color of the day is red, the blood of the Martyrs, and hence the color of the tablecloth.
The cross is upside-down compared to what most people regard as normal, but according to legend, Paul the Apostle asked the roman soldiers about to crusify him to do it upside down (feet up and head down) since he did not feel worthy to be crusified like hes master Jesus. This has since become a symbol of Peter the Apostle, and also a symbol of humility.
The stone and the keys are a reference to the name Peter, In the Bible, when Simon is called by Jesus to be an apostle, Jesus says "I tell you that you are Peter, and on this rock I will build my church, and the gates of hell will not overcome it. I will give you the keys of the kingdom of heaven; whatever you bind on Earth will be bound in heaven, and what you loose on Earth will be loosed in heaven" (Mathew 16:18-19)
The sword is a replica of a Roman sword, the Gladius. The style is specifically the Pompeian style, which was common in the early part of the first century. In other words, it is the type of sword that the people of the holy land would recognize as a sword at the time of Jesus. The Sword and book are attributes of Paul the Apostle, commemorating that he as a citizen or Rome was not crucified but beheaded with a sword. The book is a reference to the fact that the Pauline epistles are a major part of the New Testament.