pastina in Italian is a generic term for any kind of small pasta. There are literally hundreds of types and shapes (after all they are made by extrusion, so it is not difficult to diversify). They usually have cute names, like "stelline", "ruotine" and other things ending in "ine".
In Italian kitchen, pastina (that literally means "small pasta") is always eaten as part of a soup. The simplest way is to throw about 50 grams of pastina per person into boiling beef or chicken broth. It will take about 10 minutes to cook.
Pastina is considered to be easier to digest than regular pasta.