What is White Privilege?
"White privilege (or white skin privilege) is a term for societal privileges that benefit people identified as white in Western countries, beyond what is commonly experienced by non-white people under the same social, political, or economic circumstances. Academic perspectives such as critical race theory and whiteness studies use the concept of "white privilege" to analyze how racism and racialized societies affect the lives of white or white-skinned people." (from Wikipedia)
Peggy MacIntosh's exercise "Unpacking the Invisible Knapsack" is an excellent resource to get started thinking about the ways that having white skin provides certain privileges in daily life.
I'm White but I'm poor. How can you say that I'm privileged?
White privilege doesn't refer to monetary privilege. Gina Crosley-Corcoran has a great write-up of her experience with white privilege (as a broke white person) here