Tagliolini is a thin, flat pasta, similar to spaghetti but flatter than it is round. Akin to tagliatelle, the pasta typically includes egg in addition to durum wheat. The pasta is a cut ribbon (thus the name "taglia" which means "to cut" in Italian) rather than extruded.
The same sauces that are used with spaghetti may work well for tagliolini too. Use it with a simple tomato sauce or a cream sauce with seafood. Porcini mushrooms are a great addition too. One traditional preparation is Tagaliolini Salsiccia, which is a spicy tomato sauce with flavorful crumbled salsiccia (Italian sausage).
The cooking time for tagliolini varies per brand but it normally cooks in about 5 minutes.
Because there are so many pasta variations you may or may not find this in your local grocery store. Some Walmart stores sell it and you can find it at Walmart online. The dry pasta is sometimes sold as "nests" or you may find it packed flat, in long, narrow boxes. In addition to plain you may find the pasta flavored with spinach or even truffles. There are numerous online sources including Amazon.com: Pastificio Morelli Egg Tagliolini Pasta
If you can't find tagliolini you can easily substitute one of these similar pastas: