The PCF8523 is a I2C device. That means it uses the two I2C data/clock wires available on most microcontrollers, and can share those pins with other sensors as long as they don't have an address collision.
For future reference, the default I2C address is 0x68. You cannot change it.
VCC - this is the power pin. This chip can be powered by 3-5VDC so there is now on-board regulator. To power the board, give it the same power as the logic level of your microcontroller - e.g. for a 5V micro like Arduino, use 5V
GND - common ground for power and logic
SCL - I2C clock pin, connect to your microcontrollers I2C clock line.
SDA - I2C data pin, connect to your microcontrollers I2C data line.