Silver pendant, "bagua" or "pakua" medal (the eight numbers with yin yang)

The bagua (Chinese: 八卦; literally: eight symbols) or pakua is a symbol whose meanings are found in various fields of the millenary Chinese culture: from Taoism, to Feng shui techniques, to martial arts. Ba means eight, gua means number. The meaning of bagua (ba gua) is therefore eight numbers. It is generally represented with a central Taijitu, surrounded by eight trigrams of the I Ching, each aligned to a cardinal point, forming a perfect octagon. The lines that make up the trigrams can be distinguished into two types:

    Solid lines: representing positive polarity, Yang.
    Broken lines: representing the negative polarity, Yin.

The trigrams are each made up of three of these lines, assembled in eight different combinations. Each trigram can also be combined with each of the others, giving rise to sixty-four groups of six lines, the sixty-four hexagrams. These sixty-four hexagrams form the basis of the Chinese book of the oracle: they represent all the possible conditions of human life.
PA KUA - The 8 Trigrams: introduction
The ancient Chinese described the Universe with 8 elements as if they were 8 images hanging from a
wall: sky, earth, thunder, fire, water, mountains and swamps.
This representation is called Pa Kua (Pa means 8, Kua means to suspend), they used:
• a continuous line to represent the motion, the climb, strong and hard images, called
Yang
• a broken line to represent absence of movement, depression, images
faint and out of focus, called Yin
With three stacked lines they created the Trigrams:
1. Heaven / Paradise
Three solid lines. Heaven is strength and divine power. (mature yang)
2. Earth
Three broken lines. The earth is considered soft and receptive (mature yin)
3. Thunder
Two broken lines at the top symbolize thunder and glow over the mountains (the line
straight and strong at the base) (immature yang)
4.Wind
The two solid lines at the top are the wind. (immature yin)
5. Water (Moon)
The two broken lines above and below an entire line, the motion of the waters on the earth, the
stream of a river flowing between two banks. (immature yang)
6. Fire (Sun)
The broken line in the middle is the center of the fire, the two solid lines on the sides are the movement
of fire. (immature yin)
7. Mountain
The solid line represents the height and the two broken lines at the base are the ground. (yang
immature)
8.Lake / Swamp
The upper broken line is the water while the two lower solid lines are the sky.