The Porsche 964 is the company's internal name for the version of the Porsche 911

Porsche 911

The Porsche 911 is a luxury 2-door sports coupe made by Porsche AG of Stuttgart, Germany. It has a distinctive design, rear-engined and with independent rear suspension, an evolution of the swing axle on the Porsche 356. The engine was also air-cooled until the introduction of the Type 996 in 1998...

 model manufactured and sold between 1989 and 1994. It featured significant styling revisions over previous versions of the 911, most prominently the more integrated bumpers (fenders), although it was still obviously a 911. It was the first generation of 911 to be offered with Porsche's optional Tiptronic automatic transmission

Automatic transmission

An automatic transmission is one type of motor vehicle transmission that can automatically change gear ratios as the vehicle moves, freeing the driver from having to shift gears manually...

 as well as the first generation to be offered with all wheel drive.
"Type" 964 (nine-sixty-four) or simply 964 (nine-six-four) is in fact the internal code name for the car; the vehicle was badged simply as Carrera 2 or Carrera 4.