@towhoknowswhere As you are someone who isn’t used to exercise and is coming to it completely new, probably the best start is to identify what you might be able to derive some enjoyment from! Some folks get a kick out of loud music, flashing lights and pumping adrenaline in a Spin class; some like a quiet hike in the countryside; some enjoy the camaraderie and competitiveness of a game of tennis or golf; lots of middle aged and menopausal women have found huge benefits (physical and mental) from swimming in the sea, a lake or an outdoor lido. And then there’s weightlifting, running, dance classes, Tai Chi, yoga…. So much to choose from!
If increasing strength and protecting your bones are your primary goals, then some sort of work with weights would be really beneficial. You can start this at home with just a couple of sets of fairly light dumbbells and some YouTube videos. If you like it and find you’re getting stronger, you might eventually need access to a lot more weights including some very heavy ones. This might not be practical at home as weights aren’t cheap, and you obviously need space to store everything, so if you want to progress your lifting, you might need to go to a gym- I would consider using a PT if you can afford it- even if only for a few sessions just to get you started.
If weightlifting really doesn’t appeal, then you can derive some strength benefits from things like yoga and Pilates, though the effects may be more subtle than what can be achieved through lifting weights. But both yoga and Pilates have huge benefits for flexibility too, and can be great for mental health (as can all exercise really).
Hope you find something you love. Good luck!