What do the rune numbers mean?
(0/2) means that you have 0 out of a possible 2 of these runes equipped. When you have 1 of these runes equipped you will get the bonus listed under (1), and when you have 2 equipped you will get the bonus listed under (2) as well.
For instance, from your screenshot you have an item that has a Minor Rune of Hoelbrak in it. If you were to equip it, you would get an extra 10 power because you now have one of this rune equipped. If you were to then equip a pair of boots with another of these runes in it you will get an extra 10% Might Duration for equipping those boots.