(See the README.md file in the upper level 'examples' directory for more information about examples.) This example demonstrates how to utilize UART interfaces by echoing back to the sender any data ...

You've got UART access to an embedded device. Maybe you soldered wires to test pads, maybe the debug header was exposed. Either way, you have a shell - but UART is painful: Slow (115200 baud = ~2-3 KB ...