The leaves of this plant are thick and plump.
It is Crassula ovata, common name Jade or Money Plant. It is a succulent, and as such, watering should be done with care; the usual cause of yellowing leaves is overwatering, but these plants do shed leaves, so if the ones in the picture were shed from the bottom of the plant, this might be normal leaf loss. Some sun is beneficial, but despite what most houseplant guides say about needing sunlight, bright daylight is fine, with a little sun if possible.
In regard to watering, let the surface of the soil dry out slightly between waterings, and when you do water, water well, allowing the excess to drain away freely. Empty any outer pot or tray after 30 minutes so the plant is not left sitting in water. Average room temperatures are fine, but not below 10 degC at night, and preferably don't stand it near a heat source such as a radiator. More information here https://www.gardeningknowhow.com/houseplants/jade-plant/jade-plant-care.htm