Therefore my people
`am  (am)
a people (as a congregated unit); specifically, a tribe (as those of Israel); hence (collectively) troops or attendants; figuratively, a flock -- folk, men, nation, people.
shall know
yada`  (yaw-dah')
to know (properly, to ascertain by seeing); used in a great variety of senses, figuratively, literally, euphemistically and inferentially
my name
shem  (shame)
an appellation, as a mark or memorial of individuality; by implication honor, authority, character -- + base, (in-)fame(-ous), named(-d), renown, report.
therefore they shall know in that day
yowm  (yome)
a day (as the warm hours),
that I am he that doth speak
dabar  (daw-bar')
perhaps properly, to arrange; but used figuratively (of words), to speak; rarely (in a destructive sense) to subdue
behold it is I