Nippon?

Does Nippon mean the Land of the Rising Sun? Where did that meaning come from/originate, and why?

Nippon or Nihon is written in kanji as 日本, the first character meaning the sun and the second the origin. So, yes, the name means that. It seems to have been given by China, or whoever ruled what is now China, many years ago, from whose position Japan was to their east, thus, "where the sun comes from."

The origin is actually unknown. There are various theories and it is debatable. Some say it's a phonetic version of the Latin "Japon" in which probably Marco Polo or someone named to mean "land of gold" or whatever it was.

The version Marco Polo used in his journals was "Cipangu"- spellings like Japan and Japon came much later I think.

I have read somewhere that Cipangu is probably derived from a Chinese dialect version of the kanji 日本, but as Uco says, it's not known for sure.

Ancient Japan had been treated from China with the client country.
Afterwards, it is said that it is an origin that an emperor of a Japanese country at that
time declared that Japan and China are the fifty-fifty relationships. (AD.670〜)
--

Till then, China was calling Japan ''倭国/Wa country''. Moreover, Japan was calling the thing of the home country ''大和/Yamato'' and ''扶桑/Fuso'', etc.

Afterwards, a Japanese country introduced oneself in a diplomatic letter from
Japan to China.

By the way, it is said that the diplomatic letter was recorded, ''Emperor in the country (west) where the sun sets from the emperor in the country (east) where the sun rises''. This is a message to put sarcasm with ''Fall country from the prosperity country'' in the expression of a relative position of Japan and China (east and west).

Moreover, the thing that China at that time has been impoverished in the
civil war.
The background seems also to have included the thing etc. over which
China had been fighting against Japan by owning a Korean peninsula.