Mostly stretches. The key point is to just move. Get up, stretch, walk around. There’s no specific exercise really. Your body is a series of pulleys and levers. Try not to think in isolated terms when it comes to muscle structure. You can’t workout your biceps without also working out your triceps (they are opposers). Whatever you do affects your entire body.
With that said, hanging is amazing for your back. If you can hang for a min or so couple of times a day (morning and before bed), it will decompress your spine and combat the effects of gravity.