It is what they also call port replicator. It is a base with many outputs,vga, usbs,hdmi, ps2, etc. you sit your laptop in it. Here is an example
www.sony.co.uk/product/vaio-docking-stations/vgp-prs20
In that case you will need to find one for your model and make sure it comes with hdmi but this is uncommon. Not many docking stations comes with a hdmi port. To be honest I would go for an adapter.