Type supports a very important aspect of visual branding: consistency. It's the thread that holds your brand together in every media, from the first experience a consumer has when they encounter your brand, as social media drives consumers to your web site and builds perception, and internally as your brand maintains employee moral and loyalty.
If your knowledge of typography is limited to the list of typefaces (or fonts as many users call them), I recommend this hilarious video Font Conference from the esteemed cultural commentators, College Humor. It won't teach you much about typography, but does show that type has character (no pun intended).
This is typographic expression, and by extension supports your brand promise. Does your brand promise trustworthiness and reliability? Perhaps your best choice is a classic typeface. Is the promise of leading edge, forward thinking product or service? Then perhaps a serif typeface is not the best choice, but you should consider a san serif. Whether your choice is trendy or timeless, it makes a difference.
Whatever your choice, it should be different than what can be found, by default, on your computer. After all, isn’t your branding worth being different at every opportunity?