Before we dive into understanding what all these symbols mean, good news: the meaning of a planet is roughly the same as the meaning of a corresponding sign and the corresponding house. It's going to be clearer with an example.
If the planet is Mars, the corresponding sign is Aries. We say that Mars "rules" Aries, as if Mars was a sovereign and Aries a territory. So when we are learning Mars, we are learning Aries at the same time.
There will be nuances though, as Mars is the planet-energy, and Aries is, so to speak, the energy field of this planet. When someone says "I am Aries" ... what it really means is that, in their birth chart, the Sun is in the energy field called Aries, the energy field of Mars.
Aries is the first sign of the zodiac. The House that is associated with Mars and Aries is the first house. The meaning of the First House will be very similar to what Mars and Aries are about. The difference is that a house is more connected with what happens in the outer world, whereas a sign is more psychological.
We can imagine the planet as energy, the sign as the energy field around the planet, and the house as the condensation of this energy field becoming facts and events in the material world. Now, please, don't take this explanation too literally. Take it as a metaphor, or a simplified diagram.
When I am looking at a birth chart, I am looking at things that repeat themselves. For instance, if I find a chart where the Sun is conjunct to Mars ("conjunct" means they are less than 10 degrees apart in the chart) then I will understand that this Mars energy is very important.
So I will immediately have a look at the sign Aries and at the first house to see if more is happening in connection with this energy. If I find planets or sensitive points like the AC or MC in Aries and in the First House, I will understand that this Mars-Aries energy is really huge in the make up of the personality and destiny of the person. From then on, I'll wonder whether this energy is in a harmonious or disharmonious state, but we'll talk about that later.
For now, just remember that Signs, planets and houses have similar meanings.
Mars rules Aries and is the "natural ruler" of the first house. (Just notice the expression "natural ruler" and don't worry! Just remember the association Mars-Aries-First House)
Venus rules Taurus and is the "natural ruler" of the second house.
Venus also rules Libra and is also "natural ruler" of the seventh house.
Mercury rules Gemini and is the "natural ruler" of the third house.
Mercury also rules Virgo and is also the natural ruler of the sixth house.
The Moon rules Cancer and is the natural ruler of the 4th house.
The Sun rules Leo and is the natural ruler of the 5th house.
I've already told you about the sixth and seventh signs and houses.
Pluto rules Scorpio and is the natural ruler of the 8th house.
Jupiter rules Sagittarius and is the natural ruler of the 9th house.
Saturn rules Capricorn and is the natural ruler of the tenth house.
Uranus rules Aquarius and is the natural ruler of the eleventh house.
Neptune rules Pisces and is the natural ruler of the twelfth house.
Don't try to remember it all by heart, it's going to sink in quicker than you think!
In traditional Astrology books, you'll find separate explanations for the planets, the signs and the houses. Take advantage: these descriptions are but different facets of the same archetype.
Have a rest now! Speak more later...
Jean-Marc Pierson Astrologer