What is "MS" when doing macro's or copying someone else's

I use a Steelseries Rival 500 mouse when i game. I can make my own or use someone elses macro they made. However i do not understand what “MS” is when using the mouse i play with. Also when i use that mouse and software i download i like to have it auto repeat. In other words. When i press the key i have assigned it will cycle through the spell repeated until i press it again to stop

The term MS refers to milliseconds. 100 ms looks like this .100 and 50 ms looks like .050

I use the razor naga and there is a software that is configurable to adjust your macros and whether or not it plays continually or is played once every time you press the button. Lots of choices here.

I would assume your SteelSeries mouse has similar software to help configure the macros