To take a look-see means to check something out or to look at something.
According to the Oxford English Dictionary, this term comes from Chinese "看見", each letter loosely translating to "look" and "see", and entered English via Chinese Pidgin English.
Other words and phrases with the same source include
"long time no see" (很久不見 very long-time not see)
and
"chop chop" meaning "hurry up!" (速速 hurry hurry).
US southern slang. Usually preceded or followed by "now."
It means "listen to what I have to say next, because it is something that you were unware of or had previously been ignoring, much to our chagrin."
or can simply mean "look at this."
Now, lookie here: we don't appreciate that kind of foul language here.
Lookie here now: The way you're cutting them switches is all wrong. Use a sweeping motion.
Somebody with no business being someplace who's there strictly out of curiosity. Like a non-involved (not a witness) person staring at a crime scene or a fire.
"Get that lookie lou out of here, Officer Boarder! We don't need every detail on the evening news!" shouted the sergeant when she saw the guy staring at the body.