The time it should take to produce one unit if production is matched to demand. It gives the pace of customer demand. Takt time = net available production time (after breaks) per period divided by Average customer demand during that same period. Takt time is commonly referred to as the "drum beat" of the process.
If daily demand is 15 units per day, and the production process is a single shift operation with 7.5 net hours (after breaks) per day, then Takt time is 7.5 hours divided by 15 units, or 0.5 hours/unit. In other words, one unit must be produced every 30 minutes in order to satisfy demand.
The actual production rate is called the Cycle Time. Production cycle time that is lower than the Takt time will result in excess inventory. The goal is to balance all processes to run at this same rate so that there is no in-process inventory accumulation between process stages.