IIC I2C TWI SPI Serial Interface Board Port Adapter Converter Module For Arduino 1604 2004 LCD1602 Adapter Plate LCD. M.(2*1)
This board has a PCF8574 I2C chip that converts I2C serial data to parallell data for the LCD display. There are many examples on internet for using this board with Arduino. Do a search for "Arduino LCD PCF8574". The I2C address is 0x3F by default, but this can be changed via 3 solder jumpers provided on the board. This allows up to 3 LCD displays to be controlled via a single I2C bus (giving each one it's own address).