Maybe the whole site, including the surrounding buildings, is an equestrian centre, I don't know; example: https://www.openstreetmap.org/way/863798326#map=18/39.667668/2.947887&layers=P

But the area https://www.openstreetmap.org/way/1366005685 alone looks more like an outdoor riding arena. Riding arenas can belong to an equetrian centre or not. The current name "Caballos" does not seem to be a name of an equestrian centre.

If you search for "pista ecuestre" in iD you can chose from
* Pista de carrera ecuestre
and
* Pista ecuestre / Arena de rodeo
The first one is for horse racing, this is wrong here; the second one is what I think could fit here.

See also https://wiki.openstreetmap.org/wiki/How_to_map_a#Riding_centre_(equestrian)