If you have an eSIM compatible device, it means an embedded SIM is inside your device. With eSIM, there's no physical SIM card that you need to insert.
Like a traditional SIM card, an eSIM provides your connection to the Optimum Mobile network.
Some devices can simultaneously accommodate an eSIM and a physical SIM to have two wireless accounts with talk, text, and data on one device. The device needs to be unlocked for you to have two different carriers on it.