eSIM (Embedded Subscriber Identify Module) is a hardware-based mobile connectivity module, based on the SIM card standard. It has already been adopted by many major cellular networks worldwide, in addition to companies including Microsoft and Google.
eSIMs allow people to buy mobile data to use on their device in advance, so they do not need to purchase a full mobile package. Some networks around the world may also sell voice calling packages for eSIM devices.
eSIMs can be useful for purchasing mobile data when you are travelling abroad, without needing to find and purchase a local SIM card. You should check with the cellular networks in your country to determine what support they provide for eSIM devices.