Translation:Our school has around a thousand students.
It's a prepositional phrase (compound preposition):
The following two expressions have the same meaning.
around a thousand people
― alrededor de mil personas
about a thousand people
― cerca de mil personas
In the preceding examples, the Spanish word, mil, is an adjective. Next we shall look at some examples which feature this same word, this same term. Except this time, the term will be used in the role of a noun instead of an adjective.
más de mil de personas
― more than a thousand people
menos de mil de personas
― less than a thousand people
What malosopt here is saying is that without the 'de' the sentence reads "There are around one thousand students PHYSICALLY INSIDE the school", and not that "There are approximately one thousand students ENROLLED IN the school".
Essentially the 'de' is the difference between "in the school" and "within the school".
I have seen you in the Duolingo forums on other forum pages. Although I admire you for your impressive abilities and knowledge, I do not admire the six year old post written by concurso2016 in which concurso2016 introduced the readers to the dichotomy in this forum discussion that you are elaborating about.
The person that you referred to as "malosopt" five years ago has since changed their name to concurso2016.
I have doubts about whether anybody, even someone as smart as you, can provide a few Spanish sentences that can demonstrate that the dichotomy described by concurso2016 can really be illustrated with examples of sentences that include Spanish sentences which omit the word, de.
si no estuviese el "de", la oración significaría otra cosa. en este caso diría: que alrededor de las escuela hay mil estudiantes. Y realmente quiere decir: "Nuestra escuela tiene alrededor de mil estudiantes" = tiene dentro de ella = hay mil estudiantes dentro de la escuela, No! están a su alrededor. I speak spanish because I am from colombia
I think the Spanish term, alrededor, never means "round" except for when "round" = around.
- to gather around = to gather round
- alrededor de = ❶ "around"; ❷ "about"
- de alrededor = surrounding
Pero el sarpullido de alrededor está peor que nunca.
― But the surrounding rash is worse than ever.
Pero el sarpullido que lo rodea está peor que nunca.
― But the rash that surrounds it is worse than ever.
"around the corner from me" is not a very good English example of an approximation. But if your English example was not meant to be an example of an approximation, then what was the point of your example?