As said , freq is the amount of complete cycles in a time frame
of 1 sec.
Freq is measuresd in Htz [ times per sec.]
An example of this would be household current being 60 Htz [cycles per second]
Or , in England , 50 htz , etc....
Duty cycle is not by time , but by comparison of time ON to time
OFF of a cycle , So, it is measure in ratio/percentage.
A pulse of on time of 1/4 sec and off time of 3/4 of a sec. would be a duty [work] cycle of 25% or a ratio of same....