OK, you are pissed ?????

1.
Use your brain !

2.
The sender works to fast! He sends maybe the lowbyte of the word "dat" followed by "kk".
The receiver waits for one "k" and receives another byte. wrong order ?
Then the LED is 10ms on.

3.
Using software-UART paused by blinking and waiting needs a very slow sender with pauses between the characters.

4.
Use Hardware-UART inside a Interrupt-routine.