Shortcrust Pastry is a special pastry generally used to make pies, tarts or quiches, or even amazing cookies as well. Here in Italy we mainly make it sweet, so if you talk about ‘pasta frolla’ (Italian for Shortcrust Pastry) you actually mean the sweet one, otherwise you need to add the adjective salata (savory) to specify. It is made with flour and some kind of fat (in Italy, usually butter, but sometimes lard as well). It may contain eggs too, and sugar (in case you need a sweet pastry), and sometimes some leavening agent as well.
Shortcrust Pastry should have a half-fat-to-flour proportion (yes, it is a really caloric dough!). It needs to be fridge-cool, so that it won’t melt during kneading. You can replace it with lard, or some vegetable fat, like margarine or even olive oil.
Fun fact: there is a special Shortcrust Pastry we call ovis mollis, made with hard-boiled yolks, used to make especially crisp and friable.
You can also look at:
Recipe: Shortcrust Pastry