Complex sentence: It is a partially-tolled "autopista" which runs parallel to the southern Barcelona's Mediterranean coast from the intersection with the AP-7, at El Vendrell, to the intersection with the Barcelona International Airport access freeway, at Sant Boi de Llobregat.
Split into simpler sentences: It is a partially-tolled "autopista" which runs parallel to the southern Barcelona's Mediterranean coast. It starts at the intersection with the AP-7, near El Vendrell, and finishes at the intersection with the Barcelona International Airport access freeway, near Sant Boi de Llobregat.