Consider this word.
This same word, may also be written as shown below, with no change in pronunciation. The difference below is that the 'n' consonant is replaced by a 'bindu,' or dot, above the line.
Both of these spellings are correct. The bindu indicates that the vowel sound under it is nasalized. Sometimes you may see a chandrabindu is used instead of a bindu.
Here are some more examples.