Essentially uneven tyre wear, which would most probably be down to alignment issue.
Hopefully, it is just a simple case of four wheel alignment. The poor alignment could be a result for a number of reason, general road conditions which have thrown it out, worn suspension parts OR accident damage (don't get alarmed if there are no signs of repair).
When/if taking the car out for a test drive, see if it drives straight with the steering wheel straight, if it pulls to a side on a straight road, you should most definitely need wheel alignment. Also see if the steering wheel stays straight when you let it lose in drive.
Check suspension, for sounds/knocking, drive through a speed bump, this should show up any sounds if the suspension is worn.