It serves to add a nasal sound to a particular vowel.
kaan (crow) = kwN gaan (cow) = gwN
Bindee is used with kannaa, laanvaan, dulaanvaan, bihaaree, horhaa and kanaurhaa and the independent forms of vowels where a is the bearer.
EwN swN hwN kwN KwN gwN GwN ZwN cwN CwN jwN JwN zwN twN TwN fwN FwN xwN qwN QwN dwN DwN nwN pwN PwN bwN BwN mwN XwN rwN lwN vwN VwN sLwN KLwN gLwN jLwN PLwN lLwN