Level 1 is a qualification of around GCSE (D-F) or whatever the numbers are you newbies use nowadays.
Level 2 is GCSE level (A*-C)
Level 3 is A-Level equivalent understanding. Level 3 BTECs are also used to get into university.
Level 4-6, each year of university is another level higher e.g. 1st year = Level 4, 2nd Year = Level 5
Level 7 is a Masters degree level qualification
Level 8 is Doctorate/PhD level.
Bit of an overload of information but thought you'd like to see the progression of qualifications. Gives you a bigger picture