This is quite important and different for different clubs.
For a full swing shot with any club:

Your feet should be shoulder width apart for your irons and a little wider with your woods.

This measurement is taken in the heels and your toes will point out.
Not sure how wide your feet are ???
Look in the mirror.

This will ensure good balance and enable you to transfer your weight effectively back and through during the swing.

For a shorter shot with a pitching wedge for example you can stand with a narrower stance and for the little chip and run you can stand quite narrow, only 6 inches apart if you like.

Good Golfing

Anne