well you can use them for anything you use leaf veg for.

Grandmadamada , have a look at the link for google images as they are probably similar vegetables in Italy but just called a different name.

Spring greens are pat of the brassica family , a sort of cabbage but it does not grow in a tight form like cabbage normally does, the leaves have more space between them.Because the leaves are a bit seperated from each other they are sometimes a bit tougher than some other cabbages .
to prepare it , if the leaves are large then simply remove the larger leaves , wash them and cut out some of the toungher part of the central stem that runs through the leaf. this is because it can be a bit tough on the larger leaves.
I then roll the leaves and chop  through them .
the center is more tender and I simply wash and chop these.
I then give it another good rinse but without shaking off all of the water.

the way that I like to cook spring greens is to put the chopped greens in a deep sided lidded frypan with a geerous knob of butter and some seasoning , I keep the water to a minimum, as the leaves are wet and still have drops of water on them I just add a couple od spoonfulls of water to the pan..
Lid goes on and  I cook the spring greens over a slightly hotter-medium heat ( if you know what I mean) I keep shaking the pan everyso often and occasionally I just quickly lift the lid and turn the spring greens as hey cook , this is so that they cook evely and its aso to check that its not drying out, itf it looks a little dry then I just add a touch more water.
As there is ot much liquid in the an at all there is no real need to drain the spring greens after they have cooked and the added butter gives a good flavour.