eSIM means an embedded SIM. Unlike conventional SIM cards, the SIM function of an eSIM card is directly embedded into a terminal itself, which saves time to attach/detach it to/from the terminal.
With eSIM, information including telephone numbers can be rewritten remotely. (The SIM lock must be unlocked.)
*In the AG/AR series, devices embedded with an eSIM card are build-to order by designating a carrier.