I believe the best conclusion would be that the concentration of hydrogen ions in solution x is 1000 times as great as the concentration of hydrogen ions in solution y.
Solution x is acidic while y is a neutral solution.
pH is the potential of hydrogen, given by -log(H+)
Therefore, the concentration of H+ in solution x is 10^-4 while in y the concentration of H+ is 10^-7, showing that x has a higher concentration of hydrogen ions than y.