How to theme a block with product list
use devel module for better debugging option.Devel module provides dpm() which will make the array structure easy to see.When you know the exact array key where your content lies, its better to check the output with that key instead of dumping the complete vars.

so better you first do dpm(get_defined_vars());after installing devel module it will return the same what you are seeing now but in a well structure way, when you figure out the next better key of output holding the data,use dpm() on the returned array with useful key