Fruit or Veggie puree is just a variety of fruits or veggies (I try to keep it to no more than 4 different veggies), put through a blender or food processor to break it down. Dogs do not have the proper teeth to break the cell walls of veggies and get the proper nutrients out of them, hence the puree. Over-ripe fruits can be fed without puree-ing.

As an addition to kibble, if I were you, I would add as much plain cooked meats as often as possible to supplement. A bit of plain cooked chicken is very easy & cheap to feed daily.