How do you make a nasal sound in Portuguese, like the word for "mother" and "no"?

Answer 1

Physically you make the vowel sound of the letter "a" but you open up your velum. Now, that's easier said that done, but that's the physical process. The velum is the muscle that closes the nasal passage and prevents air from going out through your nose. You open it to make the "m", "n" and "ng" sounds in English.

Opening the velum allows air to flow out through the nose. Say "con" (as in "con job") and, without changing anything about the other sounds, carefully say it without the "n". The "o" is nasalized before the "n" in English. So that's the sound you are shooting for.