Learn Italian: Senza pubblicità, questo prodotto non è vendibile. - Without advertising, this product is not marketable.

It attaches to a verb stem to show that something can have that action done to it, matching the English suffixes "-able" or "-ible". Here, it takes the root of the verb vendere (to sell) and adds -ibile to mean "capable of being sold" or "marketable".

Why is it vendibile with an "i" instead of vendabile with an "a"?

The vowel you use before the -bile suffix depends on the original verb's infinitive ending. Verbs ending in -are take -abile (like lavare -> lavabile). Verbs ending in -ere and -ire take -ibile (like vendere -> vendibile and capire -> comprensibile).

Why isn't there an article before pubblicità (like senza la pubblicità)?

When using the preposition senza (without) with an abstract or uncountable noun in a general sense, the definite article is usually dropped in Italian, just as it is in English ("without advertising").

Does pubblicità also mean "a commercial"?