Hashem simply means, the name.  Some use the expression because they feel His name is too holy to say.  Others believe that if you do not use the name, Yahweh, your eternal security is at risk.  The ancient manuscripts do not reference the name, Yahweh, but rather YHVH.

Is the exact usage of the name important or can you refer to our Elohim as G-d, Yahweh, or whatever is appropriate within your language?