E – is used to start a sentence when addressing someone
he – is "a"
ke – means "the", used with words beginning with a e k o and some words beginning with an `okina or a p
ka – means "the", used with words that start with all other letters, and many words that start with an `okina, for example: ka `ōlelo and ka `āina. So, as you can see, the rules on the use of ke and ka have many exceptions and it takes time and exposure to the language to learn them all.
nā – indicates plural, more than one, of the word it modifies

Simple sentences consist of an Adjective + an Article + a Noun

Nui ke `ilio. – (Big the dog.) – The dog is big.
Pupele ke poki. – (Crazy the cat.) – The cat is crazy.
Ula ke apala. – (Red the apple.) – The apple is red.
`Ono ke kumu. – (Good the teacher.) – The teacher is good.
Wele ka lā. – (Hot the sun.) – The sun is hot.

He Pattern sentences consist of He + Noun + (Adjective) + Pronoun. No verbs are used in this construction because "is", "are" and "am" are understood. This pattern allows for specific pronouns (this, that, his her, my) rather than "a" or "the".

He aha kēia? – (What this?) – What is this?
He peni kēia. – (This pen.) – This is a pen.
He mau peni kēia. – (These many pen.) – These are pens.
He aha `oe? – (What you?) – What are you?
He kumu au. – (I teacher.) – I am a teacher.
He Hawai`i `oe. – (You Hawaiian.) – You are Hawaiian.
He Hawai`i nui `oia. – (He big Hawaiian.) – He is a big Hawaiian.

`O Keoni ko`u inoa. – (John = my name) – My name is John.
`O Kioni kēlā. – (John = this) – This is John.  (as in answering a phone)
`O kēlā `ilio ka `ilio maika`i`le. – (That dog = the dog not good) – That dog's not good.

He`e Pattern sentences consist of a Verb + Subject + Predicate, with "i" as the directional marker (to, on, of, in, etc.) between the Subject and Predicate.

Hele `o Keoni  i  ke kula.
  goes      John    to  the school
John goes to the school.

Kōkua nā kauka i kēlā kanaka me ke kino eha.
  care  (plural) doctor of that   person    with the  body sore
The doctors take care of that person with the sore body.

Noho ka wahine i  ka noho `olu`olu  i  ka malu o ka niu.
  sits    the  woman  on the chair  comfortable in the shade of the coconut tree
The woman sits on the comfortable chair in the shade of the coconut tree.