Every letter in every word is pronounced.
There are some logical results, which can be mentioned for clarification, but are not arbitrary rules.
Double consonnants (tt/nn/ss...) don't make sense & don't exist.
Double vowels make sense, some producing a double-length vowel sound which is commonly recognized in other languages.
Sounds like English
bear - not beer
Others (oo/aa) are logically OK but don't match any English sounds.
Adjacent but different vowels in one word are each pronounced with thier usual sound.
They are added together & don't produce any new diphthong sound.
As in English
Vienna - not pie/field
boa - not boat/boar
archaic - not air/pain
Adjacent vowels in adjacent words are just pronounced quite separately.
Nothing is inserted to "ease" such pronunciation, neither a separating letter (English "a man" but "an ant") nor a modified pronunciation (English "the man" & "the end" has different pronunciations of "the" with implied "thiy" before a vowel).