What do the 12 houses and 9 grahas in a kundali stand for?

houses are areas of life, grahas are the forces acting in them, and signs colour how those forces behave.

The twelve houses (bhāvas) cover the whole of life: 1 self and body, 2 family and wealth, 3 courage and siblings, 4 mother, home and peace, 5 children, intellect and merit, 6 illness, debts and rivals, 7 spouse and partnerships, 8 longevity and sudden change, 9 dharma, father and fortune, 10 work and status, 11 gains, 12 expenses, loss and liberation.

The nine grahas are the Sun (soul, authority), Moon (mind), Mars (energy), Mercury (speech, intellect), Jupiter (wisdom, children), Venus (love, comfort), Saturn (discipline, delay), and the shadow points Rāhu (desire, the foreign) and Ketu (detachment).

A reading combines these: which planet sits in which house and sign, which houses it rules, and which daśā is running. No single placement decides anything on its own.

Source: Bṛhat Parāśara Horā Śāstra; Phaladīpikā

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