The period for the second hand of a clock is 60 seconds. This refers to the amount of time it takes for the hand to sweep around the clock one time.
The word period is used in a variety of contexts to describe how much time it takes for a particular event to take place. Using another example from the clock, the period of the minute hand is 60 minutes, since the minute hand is in the same position at any given time and a time exactly one hour later. In astronomy, the periodic revolution of the Earth around the sun takes place about once every 365 days.