I have been eagerly awaiting Advent this year for several reasons. 1) It is the start of the liturgical church year (and will be the start of my first church year I'll be following all the way through). 2) I have learned the difference between Advent and Christmas songs and look forward to separating them. 3) I look forward to anticipating the birth of Christ once more. 4) I'll be celebrating the 12 days of Christmas this Christmas season and will be anticipating that as well.
Advent is celebrated on the 4 Sundays preceding Christmas. It lasts from 4 Sundays before through Christmas Eve. After Christmas, the twelve days of Christmas are celebrated in some churches, until Epiphany. Advent is steeped in tradition. Some churches have a hanging of the greens service, where the church is decorated. The evergreen symbolizes new/everlasting life in Christ.
Many churches have an advent wreath, with four outer candles (most either purple or pink) and the inner Christ candle (which is white). Some believers also have their own advent wreath at home as well. The circle of the wreath symbolizes God, His endless mercy, or eternity. The green represents our hope in God. The candles standing for the light of Christ in the world. The four outer candles represent waiting and anticipation. Purple is the color of royalty and sometimes the color of fasting; some churches use a darker blue instead of purple. Blue represents the night sky, waters, Genesis, royalty. Since purple can be used during Lent, using blue candles is a way to distinguish between the two holidays. Pink (sometimes the candle of the third Sunday of advent) stands for rejoicing.
Depending on what tradition you hail from, the candles can symbolize different things. The first candle could represent expectation, hope, prophecy, preparation. The second candle love, the third joy, and the fourth peace. Alternatively, the candles could represent Bethlehem/the Shepherds/Angels, John the Baptist/Mary/Magi, or Annunciation/proclamation/fulfillment.
Red and green, which can represent life and hope, are not official Advent colors. These colors (think holly berries and evergreens) have more secular roots and these colors are used during other times of the church year.
Advent is a time of waiting and preparation. For some denominations, only Advent themed-songs (about this hope, this waiting, this anticipation) are sung. Other "Christmas-y" songs (about the birth of Christ and the celebration) are withheld until Christmastide (Christmas-Epiphany, or December 25th-January 6th). My main source.
I encourage you to anticipate the coming of our Savior this Advent season.