I don't know the mains voltage in your country.
In the U.S. the power comes into most large industrial sites 4160VAC from the power company.
What we call switchgear is the connection/interface from that 4160V to voltage reduction components at the plant.
The transformers the plant owns to reduce the 4160V to lower voltages the plant can use: like 480V for large motors,
220V for smaller motors and plant lighting gear.
That's just a layman's terms explanation.
The reason for switchgear is to isolate the 4160VAC from the power company, from the voltage reduction equipment of the plant using the power company voltage. Without the switchgear to isolate that extremely large voltage from the
industrial plant, very bad things could happen to the plant's equipment.
Switchgear is a large contactor/circuit breaker set-up contained in one or more of the large panels in your pictures.
Maybe 'switchgear' to you could just be motor control/power distribution equipment panels to whomever you heard this term used from. But switchgear to me is what I listed above.
Probably somebody else on this site will add their input to this term(?)