男主角當然係我啦，我係 Marco
hero is of course me, I am Marco

Cantonese Sentence Breakdown

男主角 naam4 zyu2 gok3
main actor
當然 dong1 jin4
(adverb) absolutely
係 hai6
(Cantonese) to be
to connect
to relate to
to tie up
to bind
to be (literary)
to involve
relation
relationship
consequence
yes
indeed
right
我 ngo5
I
me
my
us
we
our
self
啦 la5
“now”, with an connotation of doubt
surprise
disapproval