Complex sentence: RA stands for "Raccordo autostradale" (translated as "motorway connection"), a relatively short spur route that connects an "autostrada" to a nearby city or tourist resort not directly served by the motorway.
Split into simpler sentences: RA stands for "Raccordo autostradale" (translated as "motorway connection"). A so-called "raccordo autostradale" is a relatively short spur route that connects an "autostrada" to a nearby city or touristic resort that is not directly served by the motorway.