The lower part of the cartouche means god (whether or not this would encompass goddess I don't know, but the ancient Egyptians certainly had a much wider concept of who or even what constituted a diety than most people today).
The lower symbols consists of a little stroke and a cartouche which represents a temple flag/standard. The little stroke tells us that the flag cartouche represents a single word or idea in itself, rather than being part of a phoenetic sequence.
There's loads more at http://en.wikipedia.org/wiki/Egyptian_hieroglyphs
including a picture of the god hieroglyphic in the logogram section (search the article using the word "flag" to find it).
Hope this helps