Nasal vowels and diphthongs
A tilde or a following m or n often nasalizes a vowel, so mão ("hand") and não ("no") carry a hum through the nose that has no real equivalent in English. Brazilian Portuguese also strings vowels together into diphthongs with their own fixed sounds — ei as in dei, ai as in pai, ou as in mandou — and stress and accent marks (á, â, à, ã) each signal a different vowel quality rather than just where the stress falls.
Consonants that shift with context
Several Portuguese consonants change sound depending on what follows them: c and g soften before e or i and harden before a, o, or u; the combinations ch, nh, and lh are each pronounced as a single sound, roughly like English sh, the ny in canyon, and the lli in billion; and h on its own is silent.
One broader feature of spoken Brazilian Portuguese is that unstressed syllables, especially at the end of a word, tend to be shortened or dropped almost entirely in casual speech — a pattern that shapes how the hymns sound sung aloud even when the written lyric looks fully spelled out.