What does Embedded Mean?
Embedded systems or software generally and simply means that control happens by a computer.
Embedded means that the computer is built into e.g. a machine, a vehicle or an aircraft. From the outside such embedded computers are often not recognizable as computers. This is also because the computers are purpose-bound. They can do exactly one task, which can also be very complex, namely control the machine and exchange data (parameters, measured values...) about the machine.
From the technical side, embedded systems often have a specific real-time operating systems (RTOS) or no operating system at all ("bare-metal").
In a broader sense, smartphones, for example, are also considered embedded systems to some extent. Since these are actually generic computers on which any application can run, we would not assign them to the embedded world.