Placements lacking in certain houses...What does it REALLY mean?

In my 1st house:
Sun sign Capricorn (on the cusp)
Neptune in Capricorn
Uranus in Sagitarrius

2nd house:
Mercury in Capricorn (on cusp)

3rd house:
Jupiter in Pisces
Mars in Aries

4th house:
North node in Aries

7th house:
Cancer in Earth (the symbol is a circle with a cross in it)

But Zilch, nada, nothing placed inside 5th, 6th, 9th or 12th house, except on the outside, cusps of the 5th and 6th, there are degree readings and the symbol that represents Gemini
and on either sides of 9th house there is Virgo and Libra with degrees listed. Other than that the inside of those mentioned houses are BLANK.
It says Midheaven in Libra on the cusp of 10th house, btw.

Can I get second opinions on what it means to not have anything directly placed inside the house(s), because my book didn't explain it enough?

Usually when a house is unoccupied, it means that area of life is not of particular interest to you, example, an unoccupied 5th (children) may not be a source of vitality for you.

Again, the ruler of that empty house will indicate the area of life that will affect that house. Just because the owner of that house is not there, does not mean that the house is useless.

If the house of death, the 8th , is empty, would mean that you would never die ? Impossible.

But , the house the ruler is placed will indicate the nature and reason of death or whatever is involved for the other house as well.
Another ex., your 6th is empty, which involves health and work. If the ruler is in the 3rd for instance, would mean that your work involves books, reading, intellectual activity etc... and the sign it is in will describe the quality of that work. The aspect will either bring good or bad depending.

M.C. is your career, the most important house in Astrology. If Libra is at the cusp, you will have a career in the arts, music, or whatever. But, you did not mention where Venus is placed.

Think of it like a house with 7 or 8 rooms. Some of the rooms have TV sets, some don't. Some of the rooms have beds, while others have couches and tables. One or two rooms might have stereos and computers, but not all of the rooms. There might be a storage room, a couple bathrooms, who knows? You wouldnt be concerned if the house didnt have a TV in every room would you?

everytime a planet is inside a house, the planet on that cusp takes a little part of every house on it.
in your case, it only means that youll solely have that planets influence that is in the cusp

nothing more