Meta tags are there to tell the search engines how to show your products in the
see screen shot: http://screencast.com/t/cU1VIByrEAl
If you do not enter Meta title - product name will be used automatically.
Meta description is what search engines will show in the results as description of that page.
If you do not enter Meta description - product short description will be used automatically.
Meta keywords are the key phrases people may use to search for this product.
Do not use a single word keyword (like "furniture") - more specific you will be, the better chance
you have to appear in the search results.
For example: cabana collection bed, cabana collection converted, cabana collection full size bed
You can find more technical details here: http://en.wikipedia.org/wiki/Meta_element