Advent is the beginning of the Church Year for most churches in America. Advent begins on the fourth Sunday before Christmas Day and ends on Christmas Eve (Dec 24).
The Sundays in Advent are numbered, First Sunday in Advent, Second Sunday in Advent, and so on. Tradition has given them names such as Hope, Peace, Joy, and Love, but these are not formal names and local tradition affects the designation.
The color used during Advent is typically purple (though some churches use blue).
The General Board of Discipleship has lots of information about Advent at this link.