Phalguni (फाल्गुनी/பங்குனி), the time of the fruits
The Sun (Surya) transits through Pisces annually between the mid of march and april. This one month period is called phalguni/phalguna, it means the fruits of your action. Phal means the fruit/result and guni or guna means character/quality. Sun and Moon lighting up this part of the sky represents that you’re ready to bear the results of what you were doing so far (for the past 11 months). This could make you either stay on course or move away completely.
Sun aspects Virgo and Uttara Phalguni nakshatra upon entering the sign Pisces. Also the full Moon of this month falls on the Uttara Bhadrapada and Uttara Phalguni axis that's why they call it phalguni. Phalguni nakshatras are cordial nakshatras, they represent friendliness, rapport and bondage. So the luminary axis in phalguni creates cordial relationships and bonding, dedication towards work, service, marriage/relationship etc. and on the contrary it may also release the bondage if it's not meant anymore. This is the time to gain control over the self and others. This month also brings the themes of focused energy, precision, decision making, judgemental, critical thinking, nourishment, protection, love, meditation, energizing the self (atma) and more. This is usually an energetic time to shed the past, relax and to start long term works and commitments. Sun will be exalted in the 2nd house from Pisces so its usually a happy time for sun (its like the saying "the night before the weekend is more satisfying than the actual weekend").
End of the year
Phalguni is the last month of a vedic solar year and the new year starts when Sun enters Aries. So this month is also a good time to make new decisions for the upcoming year.
Phalguni nakshatras are also strongly associated with God Shiva and it is said that Shiva and Parvati got married in this nakshatra (U.Ph.) of this month. Lord Kartikeya (Murugan) and Lord Balaji (Venkateshwara) also got married in the same nakshatra of this month. It's because the full Moon brings brightened focus on the specific nakshatra it transits over and this case the full Moon will be over Uttara Phalguni which is known for its dedication towards commitments.
Panguni Uttiram is a religious festival celebrated on the full Moon day of this month when Moon transits Uttara Phalguni. On this day the Shiva temples celebrate this festival by marrying Parvati to Shiva. Likewise, Lord Kartikeya and Venkateshwara temples also celebrate the same by marrying the Gods with their respective spouses. This is one of the best times to get married. You can also perform remedies regarding marriage on this day, even a simple milk abhishekam (pouring milk) on a lingam is highly auspicious.
Since this day and month are under the influence of phalguni, it is one of the best times to start something that you want to last long such as marriage, contracts, business agreements, buying a new item, solving disagreements, joining a work, fitness and wellness, charities, projects, connecting with people, chanting mantras etc.