What does Dips mean?
The process of immersing fabric or yarn into dye. The number of dips done to the fabric or yarn will determine the color with the more dips leading to a darker color.
Heddels explains Dips
In the denim dyeing process, dips refer to the method of submerging the fabric or yarn into indigo dye baths. In between dips, the yarn is usually exposed to the air to allow the indigo to oxidize. This process of dipping and airing is repeated until the desired color is achieved; the more dips, the darker the denim.
Here is a sample of different denim with various dip counts: