My MacBook Air is not supported by Bluetooth

Bluetooth devices such as iPhones, iPads and other Android phones do not "pair" to the Mac as do headphones and speakers. It's not a thing and never has been.

Data transfer to and from iPads and iPhones is done via direct connect with their charge cable and the Finder.

AirDrop and iCloud sync is also used for data exchange between these device.

helgemand wrote:

why is my Macbook Air not suported by Bluetooth?

In what way is it not supported?

If you are attempting to connect to another Apple device, this is expected behaviour.

While Bluetooth needs to be turned on, for many functions, pairing in the traditional sense is not required.

There are also many Continuity features.

Continuity features and requirements for Apple devices - Apple Support