I came across this particular set of what the points mean years ago, I don't even remember where. I don't even remember there being any explanations, other than the labels on the points. The definitions have come along over the years, but I'm not sure anyone could ever be finished plumbing the meanings of each point.
It's said that the septagram first appeared in Hellenic Greece, when a seven day week was adopted. Since then, it has appeared in quite a few places - alchemy, various forms of witchcraft and Wicca, math...
For me, the seven points represent, in a clockwise direction from the upper right: 1.) the Sun, 2.) The Land, 3.) the Waters, 4.) the Magics, 5.) the Winds, 6.) the Moon and 7.) the Connection that binds all the other points together.
The Sun: It is our closest star, at 93 million miles away from the Earth. It can also be said to be the creator of our solar system, when something billions of years ago set off a chain reaction that began with a nebulous cloud of dust compressing and catching fire. That single little proto-star set into motion the dust around it, where it whirled and whirled; crashed and crumbled, until the planets formed and settled into their orbits.
(I'll take that creation story any day, although Dave Sobel can tell it much more poetically than I in The Planets.)
Of course, in Egyptian mythology, the sun can be Ra, or Aten, Horus or Set (there He is again!) Ra or Aten is the sun; Horus is the rising sun while Set is sometimes the setting sun although Horus' epithet of 'God of the Two Horizons' (under his guise as Horakhty) makes Him the god of the setting sun as well.
Paula Gunn Allen calls our sun Sutalidihi, Sixkiller. Not only is She the lifegiver of the planet, but she is also a deadly thing, as deadly as an atomic bomb. There is also a Cherokee story about how the Sun was once too close to the Earth, making all its inhabitants suffer. The sorcerers tried to move it and it took four tries to get it far enough away.
We can all see this dangerous side of the Sun when we're not careful. Things left too long on the clothesline fade. Too much exposure burns us, which can lead to other, nastier things.
However, without the Sun, there wouldn't be any life. The action of the Sun's warmth at the equator causes the atmosphere to expand and move and circulate around the planet. It also feeds plants and trees, when they convert the sunlight to sugar via photosynthesis.
The Sun has its obvious associations with fire - after all, it is a big, roiling ball of nuclear energy. It is the symbol of all that is known, or out in the open, hence the saying, "Bringing it out into the light of day." It can power spells and cleanse magical objects and stones. It is symbolic of action, of power, of passion. Yellows, reds and white are its colors. It is a very powerful energy - so powerful, I've had people tell me that if you draw it down and channel its energy, it will poison you. (I haven't had any bad experiences with it though.)