[jannes]

Is aspell a spellchecker? And does this command randomly select one word from its dictionary?

(Note: I'm mostly a Windows user nowadays and I have never personally used aspell, sed, or wc)

What does the p at the end of the line do? Is that a mistake or is it there on purpose?

[loumf]

The p prints the randomly chosen line -- wc -l is the number of lines in the file, (random % lines-in-file) picks a random one, 'sed -n 30p' prints the 30th line.