The meaning of "宝藏"?
藏 has two meanings:


as a verb (cáng), it can mean to hide, to conceal, etc.
as a noun (zàng), it can mean depository, such as 宝藏 (bǎozàng).


Of course the two meanings are related. 

To get an impression what this word means, search for 宝藏 on Google Image search or Baidu Image search.