The timer frequency indicates the timer precision and resolution. For example, a timer frequency of 2 million ticks per second equals a timer resolution of 500 nanoseconds per tick. In other words, because one second equals 1 billion nanoseconds, a timer frequency of 2 million ticks per second is equivalent to 2 million ticks per 1 billion nanoseconds, which can be further simplified to 1 tick per 500 nanoseconds.
The Stopwatch.Frequency value depends on the resolution of the underlying timing mechanism. If the installed hardware and operating system support a high-resolution performance counter, then the Stopwatch.Frequency value reflects the frequency of that counter. Otherwise, the Stopwatch.Frequency value is based on the system timer frequency.