A mobile hotspot is a feature available on smartphones and dedicated devices that allows you to share your cellular data connection with other devices via Wi-Fi. Essentially, it turns your device into a portable internet router, using the cellular network to provide internet access.
When you activate the mobile hotspot feature on your phone, it creates a Wi-Fi network that other devices can connect to, just like they would with a home Wi-Fi network.
This connection is facilitated through a process called tethering, which can be done wirelessly or via USB or Bluetooth, depending on the device and service provider.