"For prayer is nothing else than being on terms of friendship with God."  Saint Teresa of Avila

The word "novena" comes from the Latin word novem, meaning nine.  A novena is a 9-day prayer devotion or focused prayer, often prayed in preparation of a feast day or for a specific intention.  Novenas are commonly prayed through the intercession of the Blessed Mother or of a particular saint, but all novenas are offered to Christ.  Either the same prayer is prayed for all nine days or a list of prayers are followed for each day.

Every novena is a bit different in the intention, formation of prayers, and practice.  In some Catholic communities where novenas are a popular part of the culture, traditions may include lighting candles, decorating statues, participating in processions, singing hymns, and joining in fiestas.

Here is EWTN's links to some of the most popular novenas: https://www.ewtn.com/catholicism/devotions/novenas-75