Nasal sounds are produced by blocking the air in the mouth and allowing it to resonate through the nose. Nasal sounds are consonants and almost always involve voicing.
Examples of nasals include m, n, ng, which are common in English.
Australian Indigenous languages often have more nasal consonant sounds than English, including a retroflex nasal (written either rn or ṉ) and a palatal (usually written either nj or ny).