What does it mean to have 2 letters or 2 numbers in a password?

"Letters" are the 26 marks from 'A' through 'Z'. (A, B, C, D, E, . . . and so forth.)

"Numbers" are the 10 marks from '0' through '9'. (0, 1, 2, 3, 4, . . . and so forth.)

When you choose your passWord, you're supposed to put two of the first kind

of marks, or two of the second kind of marks, in the passWord.