BLE is short for Bluetooth Low Energy, a communication stack designed specifically for communication between IoT devices that support BLE.
The BLE stack builds on four simple, but powerful, concepts that can be combined to create a wide range of network topologies:
Advertising: A BLE device can advertise about itself. The advertisement can contain a list of services and a manufactorer data section.
Scanning: A BLE device can scan and discover nearby BLE devices for advertisements.
Service: A BLE service is composed by a list of characteristics, exposed by a BLE device as a service.
Characteristic: A BLE service attribute containing a value that may be readable and writable from a client.
If you are using the open source version of Toit - optionally through Jaguar - you can find a working example in the source repository. The example simulates a BLE heart rate monitor and can be found here.