What it means
A Varshphal chart is a solar return: it is cast for the instant the transiting Sun comes back to the exact degree it held at birth, which falls within a day or so of each birthday. The whole annual reading — the Muntha, the Tajika yogas, the Mudda dasha — comes from that single chart.
How it is read
Years are counted from birthdays, not calendar years, and this is where readers go wrong. Year 30 is the year that begins on your 30th birthday and ends on your 31st, so the year you are living through carries the number of your completed age.
What to watch for
The technique is called Tajika, and it entered Jyotish from Perso-Arabic astrology around the 13th century rather than descending from the Sanskrit classics. Its aspect rules, orbs and yoga list are its own, and they differ between Tajika Neelakanthi and later authors — so two Varshphal readings can disagree in good faith.