This is a nice-looking coin from the Indian Princely State of Mewar. Aada aana is the denomination: half anna. The date is VS1999 on the Vikram Samvat calendar, which corresponds to 1942AD on the Gregorian calendar.
These coins carry low value now, but, in the future, as more and more people discover the fascinating area of Indian coins, my guess is that the values will go up substantially. Today's catalog values look like this:
worn: less than $1 US dollar approximate catalog value
average circulated: $1
well preserved: $3
fully uncirculated: $8
To convert these catalog values to actual buy and sell values, use the information on our Terminology page.