What it means
To kit something out means to fully equip it, not just chuck in the bare minimum. You use it for people, homes, vans, offices, whatever, when it's been sorted with all the bits it needs and often a few extras too. It gives off properly prepared, ready-for-anything energy.
Usage examples
"Mum’s kitted me out for the festival, new wellies, poncho, and a massive charger. I’m ready for mud, rain, and dodgy signal."
"Dad kitted out the camper van with a kettle, a tiny fridge and a fold-down table, and now mum refuses to camp in anything else even in the pouring rain."
"The new flat came bare, so we kitted it out at the charity shop down the road, two sofas, a kettle and a wonky lamp, all for less than a takeaway."
"We kitted out the spare room for my brother before he moved back, desk, lamp, duvet, the lot, so he couldn't moan about a thing."
"She’s kitted the dog out for winter in a little coat and flashing collar, proper overprepared but fair play, he looks sorted."
Where it comes from
It comes straight from kit, the old English word for gear, clothes, or the bits you need for a job. From there, kit out settled into British English as the natural way to say someone or something’s been fully equipped, dressed, or fitted up properly for whatever’s coming.