How to Mesure the smoothness of a signal so how can i determine if a signal is smooth or not ? And if its possible to get something indicating the level of the smoothness of my signal.

I looked at the r-squared and hurst exponent but i wanted to know if they where others methods.
Hurst exponent is a good option.

For a better answer you must better explain your objective. For example if you are comparing signals and if they have the save length, amplitude, sampling frequency and/or others.

If you are looking for very simple approaches then, for example, you can:


calculate the discrete derivative 
calculate absolute value
sum all values


Another option could be:


apply a low pass filter
calculate difference between original signal and filtered signal
a smaller difference means a smoother signal.