This HC-05 is both a master and slave module. In master mode other devices can connect to it, In slave mode, it can connect to other devices.
The module is controlled through the use of AT commands.
VCC: 3.6V to 6v Max
TXD: Transmit Data
RXD: Receive Data
KEY: this pin is used to change the mode of the Bluetooth module.
EN: This is the Enable Pin – High Level to Enable
Quick Flash = Module disconnected
Double Flash = Module connected
Slow Flash = Module in Command Mode
Power supply input is 5V maximum.
Datasheets and AT Commands are readily available via an internet search.