Baruch ("bah-ROOCH" with a German "ch" sound at the end)
"Baruch" means "blessed."
"Hashem" means "the name."
It's a way of saying "thank G-d."
Hashem is the word we use to refer to G-d in everyday normal speech, as opposed to the many names he has that we use during prayer. Since we are mere mortals, and can't really bless Hashem, the word "baruch" when used to refer to Hashem usually means that Hashem is the source of all blessings.