context for this situation. "en pige" is singular so you would want the singular pronoun of "det" instead of the plural "de". In English "They are a girl" wouldn't make much sense.

Normally "det" is used for both but you can say "dette" for "this" though it is almost never used

*Han=He

Gender in Danish is a grammatical feature of words. It's not based on any criterion that makes sense, as in English, it's just something you have to learn.

PS: While gender works differently in Danish, this sentence isn't actually an example of the difference. Consider "THAT is a girl".

Any sentence like "it is a [noun]" should be translated as "det er en/et [noun]"

In the construction "it is [adjective]" the use of den/det depends on the genus of the noun that is referred to e.g.:

The tire is flat = dækket er flat; it is flat = det er flat

The boat is sinking = båden synker; it is sinking = den synker

Think baby balloons... "it's a girl!" (I'm not advocating for this usage... just saying that it also exists in English)

Consider ''THAT/THIS is a girl''.

Yes, you are right, prabhleen12, one would normally say "she is a girl"; but in English it is common to say "It's a boy", or "It's a girl" when referring to a newborn baby. It's the same in Danish.

That would be ''Hun er en pige''.

No. "Det er..." means "That is...", whilst "Der er..." means "There is...".

Consider ''THAT/THIS is a girl''.

"Denne" for common gender, "dette" for neuter gender.

Stol - en stol - stolen - denne stol.

Bord - et bord - bordet - dette bord.