.. of no importance

Cartesian method of reflecting.

Trying to understand and learn English for dual terms like slot while sign, meaning and significance ...

The "slot" is a term that has a dual nature, but its primary function defines it as a process or concept and not as an object:

Slot: Process vs. Object

Slot as Object (Noun): Yes, it names a physical object (like the SIM Card tray or the RAM slot). In these cases, it is an object.

Slot as Process/Function (Concept): In a more fundamental sense and throughout technology (data network, TDMA, CPU scheduling), the "slot" is the process or the rule of organization, reservation, and allocation of a resource.

What makes the term so generic is that it describes the act of reserving (the process) for any domain:

Physical Domain: The process of reserving a space.

Temporal Domain: The process of reserving a time.

Logical Domain: The process of reserving an address.

Therefore, even though the physical tray (slot Sim/ an object) is real, it exists by virtue of the process of reserving a place for the chip. The slot is fundamentally an organization process.