Asana is a body position in Yoga. It can mean where a person sits, and the way that they sit. It helps to balance the mind and body. It is meant to be firm, yet comfortable.
That is different from sport, traditionally more already helping into starts, being meditation.
All the many different body positions in Yoga are Asanas: they all have their own names and every name ends with asana, such as Savasana (correct lying). Many have names of animals - such as bujangasana (cobra), or other sirssana (headstand).