The 6th Swapna seen by Mata Trishalā is generally understood as the Moon (Chandra).

Meaning

It symbolizes:

• Peace and calmness
• Coolness and purity
• Brightness of wisdom
• Auspiciousness
• The coming of a महान आत्मा who will bring spiritual light into the world

In Jain tradition, this dream indicated that the child to be born would be highly pure, radiant, and spiritually uplifting, like the moon spreading gentle light in darkness.

Note

In some Jain traditions, the order of the 14 dreams is explained slightly differently, but the 6th dream is commonly the Moon.

If you want, I can also list the full meaning of all 14 dreams in simple language.