"You are running out of disc space on recovery D", what does that mean?

hard drive D (which on your laptop is named “recovery”) is full.

How do I empty it (I’m a techno-tard).

Ahhhhh now that is much more complicated question. You need to work out what is saving stuff there in the first place and why. A lot of laptops come with a seconf parttion on the hard drive that contains all the files needed to reinstall the operating system (which is what this sounds like possibly). In that case the manufacturer might have used a partition exactly the right size so as not to waste space on the drive that you could use and has filled it with all the files to reinstall the operating system and left no empty space. When windows views it, it gets upset because it likes a bit of empty space on drive even though in this case you don’t need any.

Take a back up delete it or move to some other drives

Just shift some of the files to C Drive. Give some space to D Drive.