results in overpass-turbo-api : interesting data tells us more things

You looked for all nodes, ways and relations which have a key "school" (school=*) in a specific area specified by a coordinate bounding box (see s,w,n,e parameters in your query code on the left). The circles represent the location of those objects. You also could click on the circles to see this object's tags.

Note that just in case you are looking for schools you should rather search for all objects which are tagged amenity=school as school is just a subkey of this (see its used values).

In case you are unfamiliar with Overpass turbo, see our wiki page about it, specifically the "Map key" section of that page which explains what the different circle colours mean.