can somebody help with pinout what is RXD and TXD

Hardware Arduino Zero
1

I have this board

there are two holes for pins next to regular TX and TR, they are not connected

how to use it as serial port, which one ?

2

Hi ED201,

The extra holes are an additional serial port (Serial). The TXD and RXD (on the female header) are Serial1.

An WeMos M0 serial ports are described in this tutorial: WeMos SAMD21 Arduino M0 Quick Start Tutorial.