In Jainism, "6 Kayna" refers to the six types of bodily existences or classes of beings (six types of bodies), which are:

1. Prithvikaya (Earth-bodied beings): Living beings whose bodies are based on earth element, like earth-bodied souls in soil, clay, etc.
2. Apkaya (Water-bodied beings): Living beings whose bodies are based on water element, like souls in water, dew, etc.
3. Teukaya (Fire-bodied beings): Living beings whose bodies are based on fire element, like fire, lightning, etc.
4. Vayukaya (Air-bodied beings): Living beings whose bodies are based on air element, like wind, breeze, etc.
5. Vanaspatikaya (Plant-bodied beings): Living beings in plant life, like trees, bushes, vegetables, etc.
6. Trasa-kaya (Mobile beings): Living beings that can move, like insects, animals, humans, etc.

These six types illustrate the Jain principle of Ahimsa (non-violence), by acknowledging that life exists in many forms, not just in humans and animals, and thus should be respected and protected.