Usually when you navigate between and within controls speech is interrupted automatically, presenting the next element in focus. You can also interrupt the speech at any time by pressing the [Ctrl] key momentarily.
Once you have used SpeakOn for a while and can find your way around the system easily, you can reduce verbosity by adjusting the information and control tip levels.
This is done in the Main menu Global settings and is explained in this Tutorial:
Global settings > Changing settings for information and control tip messages