Hi Bartimaeus26 and welcome.
It is 2GB of dedicated video memory that can be expanded when required by using available system RAM.
The NVIDIA® GeForce® GT 540M GPU comes with 1GB or 2GB dedicated memory (Sony charge an additional £80 for the 2GB version).
As you say, there are no details given for total video memory available for the 2GB version but for the 1GB version Sony say "Approx 4095MB Total Available Memory using system memory"
It does not look like the VPCF23P1E is still available on the Sony website and you may need to configure your own specification here under the '1 model found' Tab: -
http://www.sony.co.uk/product/vn-f-series/tab/models
