“Pongal” is a four-day long festival in Tamil Nadu dedicated to Sun God, usually celebrated from January 14 to January 17 every year.
It is also called a harvest festival as during this time crops like rice, sugarcane, turmeric etc are harvested.
In the Marathi language, you can wish someone “Happy Pongal” as “पोंगलच्या हार्दीक शुभेच्छा”.