Learn Italian: Non c'è niente sul tavolino. - There is nothing on the small table.

We drop the final -o of tavolo (table) and add the diminutive suffix -ino. This suffix is used to make things smaller or sometimes cuter. So, while a tavolo is a standard dining table, a tavolino is a small table, such as a coffee table or a little café table.

Why do we use both non and niente here? Doesn't that make a double negative?

Yes, but in Italian, double negatives are grammatically correct and often required! When a negative word like niente (nothing) comes after the verb, you must put non before the verb. Literally, it translates to "There isn't nothing," but in English we just say "There is nothing."

Where does the word sul come from?

Sul is an articulated preposition, which just means it is a preposition combined with a definite article (the word for "the"). It is made by combining su (on) with il (the masculine singular article for tavolino).

What exactly is c'è?

C'è means "there is." It is a contraction of ci (there) and è (is). If we were talking about plural things, we would use the plural form ci sono (there are).