Probably the easiest way to explain what direct port injection is, it is the inclusion of a second high pressure fuel injector which squirts fuel directly into the combustion chamber instead of via the traditional port method. Yes you read that correctly, this 4 cyclinder engine has 8 fuel injectors. This is done to provide a much better throttle response.

Here is a video released by Toyota NZ explaining it better, along with some other things about the brz drivetrain.

Obviously there is allot more to it, but at a very high level that is what direct port injection is.