Learn Spanish (Latin America): La niña es de Colombia.

Niña (girl) is a feminine noun, so it needs the feminine word for "the", which is la. El is the masculine word for "the", which you would use for a boy (el niño).

Why do we use es for "is" in this sentence?

Es is the "he/she/it is" form of the verb ser (to be). We always use ser when talking about a person's origin, like what country they are from.

How exactly does es de translate to "is from"?

In Spanish, the little word de often means "of" or "from". When you pair it with a form of the verb ser (like es), it tells us where someone originates. So, es de Colombia literally means "is from Colombia".

Could I use the pronoun Ella (She) instead of La niña?

Yes! If the listener already knows who you are talking about, you can replace La niña (The girl) with the subject pronoun Ella (She) to say Ella es de Colombia. Because the verb es already points to "he/she/it", you can even drop the pronoun completely and just say Es de Colombia.