Dasha hara is a sanskrit word which means removal of ten bad qualities within you:
kama vasana (lust)
krodha (anger)
moha (attachment)
lobha (greed)
mada (over pride)
matsara (jealousy)
swartha (selfishness)
anyaaya (injustice)
amanavta (cruelty)
ahankara (ego)
it's also known as vijaydashmi means vijaya of dashmi.
happy dussehara!