In the US it's known as "Szechuan peppercorn". Preparing it for use requires carefully inspecting a handful for stems and thorns (which can be quite big), pan toasting and crushing/grinding to a coarse powder.

As pointed out in the sister comment, the spice has a mild numbing effect which counters the heat of chilis. Adding a little to hot dishes makes the flavor more complex and enjoyable.

For people who like to cook it's an ingredient worth experimenting with across culinary boundaries.

It looks like sancho is the berry produced by the tree. The leaves look similar to our toothache tree or Hercules Club as some call it. I know that the bark here in NAmerica has been used as a local anesthetic for a long time. It produces a tingly, numbing sensation when it becomes wet. I have used the bark to numb gums or throat pain. I never tried the berries.

My tree here died in the last drought. It was a birdshit variety since it was growing along the fence. The seed was dropped by a bird as it rested on the fence and I got a tree as a result! Gotta wait for the next one I guess.