Object?

With 'be', neither sentence has an object. Your first sentence is wrong. They should read:

It's full of wise people.-- There is no object. 'Full of wise people is a predicate adjective
There are wise people. -- 'There' is an existential subject; the real subject is 'wise people'.

Thank you Mr. Micawber. Now, what is puzzling me is why do we say it IS but not there is wise people? I know we have to use is after it, but for some reason it's confusing. I feel so bad because I've asked probably the easiest question in English.

'People' is plural; the singular is 'person'

There are wise people.
There is a wise person.

Is that what you are wondering about?

Well, what I'm wondering is;

There are wise people.

It's full of wise people.

I know that I cannot write there is wise people. So far so good, but why do we write It's full of wise people? Why is the verb in singular form?( Of course it's because of 'it', but would it not be better if we changed it?)

"It" is the subject.
We dont' know what "it" is - a room, a committee, a city... doesn't matter. It's a singular thing or place.

"It is full of wise people" is not a cleft sentence with a dummy "it" the way "there" is not the "real" subject. "It is full of wise people" means there is a real "it" somewhere.

Thanks Grammar Geek. Since it is the subject of the sentence we use singular verb.

Grammar Geek"It is full of wise people" is not a cleft sentence with a dummy "it" the way "there" is not the "real" subject. "It is full of wise people" means there is a real "it" somewhere.

Sorry, I don't get this part.

Mister MicawberThere are wise people. -- 'There' is an existential subject; the real subject is 'wise people'.

As MM said above.

I really, really beg both of your pardon. I really have no idea why I overlooked MM's that point. Sorry again.