I, you, he/she, we, they — and the three different shapes each one takes depending on its job in the sentence.
Ilokano pronouns change form depending on what they're doing in the sentence: a full nominative form (used as subject, often at the start), a shorter enclitic form (attached right after the word before it), and a possessive/agent form (for "my/mine" or "by me"). This app's own dictionary spells all three out for every pronoun — here are the core ones.
siák / -ak
I / me
full nominative siák, enclitic -ak
siká / ka
you (singular)
full nominative siká, enclitic ka
isú / isu (or dropped)
he, she, it
the enclitic form is often just silently dropped
dakamí / kamí
we (not you)
excludes the person being spoken to
dakayó / kayó
you (plural)
isuda / da
they, them
The possessive form ("my book") and the agent form ("I did it") are usually the same short word, attached after the noun or verb.
ko
my / by me
possessive & agent form of siák
mo
your (sg.) / by you (sg.)
possessive & agent form of siká
na
his/her / by him/her
possessive & agent form of isú
da
their / by them
possessive & agent form of isuda
To show who owns something, the possessed noun comes first, then the possessor. If the possessor is a name, a possessive marker (ni for a person, ti for a common noun) goes between them; if it's a pronoun like na 'his/her', no marker is needed at all.
diáy baláy ni Pédro
the house of Peter / Peter's house
diáy baláy ti bakét
the house of the old woman
diáy baláy na
his house
Grammar: Ch. 3.2(e); Ch. 11.1(a), from Constantino's Ilokano Reference Grammar (1971, CC BY-NC-SA 4.0).