This breakout board allows the ESP8266-01 module to be programmed via a USB-UART cable (FTDI), making the whole process easier compared to bread-boarding.
A jumper allows selection of 3V3 or 5V0 as input voltage coming in via the FTDI cable.
Another jumper allows level shifting of the 5V0 TX signal from the computer down to 3V3 to make it ESP=8266 safe.
For more details, follow the original project by @technolomaniac : https://hackaday.io/project/5728-esp8266-01-breakout
Project files are available on Github.