That appears to be Aeonium; its probably dropping leaves because its suffering transition shock. That occurs when you move a plant outdoors if its too cold for it, and in reverse if its moved to a warm room.

These are better left to rest over winter in a cool but frost free place, they don't really appreciate hot rooms inside. Reduce watering to give it a chance to go dormant, and if you can, find somewhere cool to stand it.

Is it only losing leaves at the very lowest parts of the rosette? If so, this is normal growth. They drop the bottom leaves and grow from the top. Aeonium are winter growing plants in the Canaries where most of them originate, so they tend to go dormant when its very hot. Mine have grown a lot over this autumn period (in my greenhouse) and every week I have to go in the greenhouse and remove the lowest leaves which have shrivelled up...most have already fallen on to the pots and I just collect them up and bin them. They also require regular watering when in growth, so don't let them get too dry for too long. And maximum light, so outside in a greenhouse is best in winter (or a conservatory) as long as you can keep it frost free. Yours looks good enough...maybe a little bit light-starved. Don't let it get too wet, but look out for it drooping and then water it...allow it to dry out in between. I think I can see some damage on the very top shoot...the 'leader' as it were. It looks like that has lost its foliage. I'd cut it back to a healthy shoot and allow it to callous over. As Bamboo says...possibly temperature change has got to it, or maybe over watered a bit? But you won't kill it by keeping it indoors. I have done that with several for several years now. They don't like it that much, but they will survive and its better than letting them get frosted which will certainly kill them. I almost lost one of mine (and I have loads!), and it was a plain green one. I think it is a weaker growing plant and it also dislikes temperature change more than most of mine. But I think yours is going to be fine. :)

Aeoniums, like most succulents, need pretty intense light to stay healthy, too. I would try to give it as muchdirect sunlight as you can, or put a high intensity (150 watt equivalent) full spectrum lamp on it.

You might find this of some assistance - it refers to the black leaved variety, but the same advice applies to yours

https://www.telegraph.co.uk/gardening/problem-solving/how-to-keep-your-aeonium-over-winter/