Is the plural of 'it' 'they'?

When somebody is talking about he or she sold some boxes, what's correct?:

'I sold them'

or

'I sold it'

Because sellign only one box would be:

'I sold it'

"I sold them" is correct, since there are more than one of them.

Yes, "them" can be the plural of "it".

Please you help I for the english to speak gooder because I has difficult to it.

There are two plurals of "it". The word "it" is used as a subject or an object in a sentence or question. The word "they" is only used as a subject while "them" is used only as an object.

If you sold one box, say
"I sold it."

If you sold more than one, say
"I sold them."

To illustrate the use of "it" and "they" as subjects let's use the passive voice.

If you sold one box, say
"It was sold."

If you sold more than one, say
"They were sold."