If so, could anyone give an example pls?
It is almost never appropriate to use it for a person. Sometimes, we seem to use it when asking about somebody's gender. E.g.:
A: My wife's had a baby!
B: Is it a boy or a girl?
A: It's a boy!
but here it is just a dummy pronoun.
If you don't know the gender, you have the following options:
- Use an arbitray gender and stick to it (usually he).
- Use he / she.
- Use they. (This is the most "natural" way for native English speakers, although some consider it a little informal.)
- Use a descriptive noun. E.g. the customer.
Note that it is very offensive to refer to transexuals, transvestites, hermaphrodites, and so on as it. If the person adopts a male name, use he. If the person adopts a female name, use she.