aria-label, aria-labelledby, and aria-describedby can all be used to bring extra clarity to a given element when it's exposed to assistive technology.

• aria-label overrides an element's name with contents you specify.
• aria-labelledby replaces an element's name with contents from another node on the page. You'd use this when you'd already have a visible label anyways.
• aria-describedby sets your element's description to the contents of another node on the page. This is great for noncritical, supplemental information.
• aria-description… is coming.

As always, avoid ARIA whenever possible.