The planets are considered to represent basic urges, whereas the signs represent the way those urges manifest in a person's life. The house is the area of life in which the manifestation takes place (usually). Another way of looking at it is that the planets are the people, the signs the costumes they wear, and the houses the stages on which they act out their parts. For example, the first house represents how we appear to others and how we think of ourselves. It is our outer persona. Therefore, the Sun in the first house will indicate a person who is showy, warm and "larger than life". It will produce a masculine (yang) type of aura. Whereas the Moon in the first house will indicate a person who is intuitive and shy, with a feminine (Yin) type of aura. Of course, all this must be balanced with the other elements in the chart.
To see interpretations for planetary bodies in the twelve houses used in western astrology, click on one of the links to the right. If you are looking for interpretations in another zodiac, look up the associated tradition.