A Sabbat or Pagan Holiday is a holiday. It is celebrated in many diffrent ways by many diffrent traditions. The Sabbats can be mapped out in the wheel of the year. The wheel of the year tells the story of life, death, and rebirth.
The wheel begins to turn at Yule also known as the Winter Solstice. During this time the God is born. In this innocent state he is pure joy. His birth anounces the returning light. At Imbolc or Candlemas growth is celebrated. This is the time when the days are longer. Next is Ostara the child is now the Green Man. He is a strong youth who courts the Goddess in her Maiden aspect. Beltaine marks the time of marriage, maypoles, and bonfires. The Summer Solstice, also know as Midsummer marriage is consummated. Now is the Coronation of the Summer King. He is no longer the child born to the winter. At Lughnasad The Sacrifice of his life is mourned. Mabon is the time of his sleep within the womb of the Goddess. Samhain is when he travels to the summerlands. A time for him to grow young again and a place to wait until he is born again at Yule.
This is but a short description of the wheel of the year. It can be defined in many different and beautiful ways. Every culture celebrates differently. Each is unique. Just as all of us are.