Main water shutoff valvel leak ?

[SIKSUKR]

Ball valves almost never leak past the ball itself. Your leak is probably a very simple packing nut leak and probably only needs a slight tightening of the stem nut. Typical ball as shown has a nut holding on the handle. Take both off and turn the nut underneath clockwise looking down onto the nut. Dont over tighten. It usually doesnt take more than a very small amount of turning to stop it. You should be able to tell as you do it. Pop the handle back on before securing it with the nut and try the valve a few times to see if you have fixed it. Congratulate yourself!