When you are making a speech or presentation, you need to be aware that your gestures can support or detract from your message.
Learn to become aware of what your hands are doing while you speak.
If necessary, make yourself hold them still.
Many people have habits that are terribly distracting and yet they aren’t aware of what they are doing. They click or twiddle a pen, play with their hair or their clothes, hold a microphone with fingers unconsciously making a rude gesture, take glasses on and off, put hands in pockets and take them out.
All of these things are not necessarily detrimental in themselves, if the audience is absolutely focused on the speaker and the message. But if there is any reason for the audience’s attention to stray (and we all have short attention spans) then they will become fascinated, at best, and possibly annoyed at whatever it is that the speaker is doing with their hands.