You are using a little endian CPU, the 16 bit words hexdump is showing are byte swapped.
6 is the offset of the second dump line which is empty, your file containing only six bytes.
Use od -c or od -t x1 to get the expected order:
$ od -c test.txt
0000000 p r o v a \n
0000006
$ od -t x1 test.txt
0000000 70 72 6f 76 61 0a
0000006