One way is to use the Text tool and place it on a copper layer.  Then remove the solder resist in the whole area

Another is to simply add the tracks drawn to reproduce the text then, as Mike says, remove the solder mask over that area. However, if you do it using tracks, they will probably be removed every time an Update PCB or Import Changes is done. To prevent this, create the required text and characters in a PCB Footprint in the same way as directly on the PCB. Save it as something like "SN_BLOCK". Then create a schematic symbol to represent the serial number block and assign the name "SN\_BLOCK" to the "Package" attribute of the symbol and save the symbol also with the name "SN\_BLOCK"\. Place the symbol in the schematic and do Update PCB to pull the symbol into the PCB. You can do the logo the same way. For more, see (2.2) and (4) in: [https://easyeda\.com/andyfierman/Welcome\_to\_EasyEDA\-31e1288f882e49e582699b8eb7fe9b1f](https://easyeda.com/andyfierman/Welcome_to_EasyEDA-31e1288f882e49e582699b8eb7fe9b1f)

@MikeDB Thank you!

@andyfierman Thank you!