Any info on what this is and how to look after it would be greatfully appreciated. It's not for me, but on behalf of someone else, honest!

It's a garden balsam (Impatiens balsamina). An annual of the Busy Lizzies family. Not sure I have a lot of info though. I found on the net that it tolerate sun or shade but needs to be kept well watered, in a humus rich neutral soil.