In its own right slate offers interesting colours and texture variations, and you might be able to make the best of its presence, but here it looks odd. Maybe the renovators had a few left-over tiles after doing the front wall. I'd be investigating at front and rear whether slate is covering any defects and whether it was created any problems. I would not just paint it over.

Hi Caitlyn, I agree with rwalton that you should probably remove the slate and check out what's behind it. That high narrow window suggests the room behind the slate might be a toilet, bathroom or laundry? In which case, the slate might be covering pipes that need some work. If you're confident that's not the case then I'd just paint it the same colour as the wall and stick a nice shrub in front of it.

Is that rising damp all along the wall below the row of slate tiles? I would not paint that over without investigating first.

They look like camouflage bandaids on the walls. I'd remove them altogether, find out what's behind and then patch up render.

We would recommend two choices - matching your wall colour with a tone of the slate and your roof or you could have the slate removed as well a plasterer to fix and repair the patches then you are not limited by colour selection to match in the slate.

A possible use for the slate if you choose to leave it there would be a floating seat (painted black like your roof) just below the slate - use the slate as a seat back or continue the slate up and create an outdoor BBQ area with the slate as a splash back for the BBQ.

You could also install a floating bench (but check the weight bearing possiblities of the wall). A great landscape designer &/or builder could help you with a concept plan - good luck! The yard looks like a great space - BBD