According to Hasthalakshanadeepika, the classical treatise on dances, there are 24 basic mudras or hand signs used in Kerala dances. These Mudras are used in the classical dance dramas like Kathakali, Kutiyattam, Nangiarkoothu, Mohiniyattam and Ottanthullal.

Holding all fingers straight, stretching the thumb sideways is Hamsapaksha.
 
Hamsapaksha using both palms indicates :
Moon, cupid, wind, the Devas (Demi Gods), mountain, valley, daily, relative, bed, stone, pleasure, chest, breasts, dress, take, deceit, lying down, fall, populace, thrash, mole or bodily mark, escalate, establish, come, welcome, bathe, sandal paste, embrace, retreat, govern, send away, mace, cheeks, shoulder, hair, humility, blessing, sage, fish, worship and tortoise.

One palm indicates :
Thou, sword, anger, now, I, in front, flame, call, waist region and prevent.