Purva Ashadha is nakshatra number 20 of the 27 lunar mansions in Vedic astrology, spanning 253.33° of the zodiac in 13°20' steps. Its planetary lord is Venus and its presiding deity is Apas.
The Moon's position in Purva Ashadha at birth shapes the Vimshottari Mahadasha sequence — a Purva Ashadha birth begins life in the Venus mahadasha, with the balance of that period decided by how far the Moon had travelled through the nakshatra.
Use the free Kundli generator to find whether Purva Ashadha is your janma nakshatra, and the Panchang to see exactly when the Moon transits Purva Ashadha on any date.