Inspiration

The message is encrypted by converting the plaintext into numbers based on the alphabetical order of the individual letters. Then 1 is added to these numbers and these increased numbers are converted back into letters. To decrypt, we convert the letters in the ciphertext into numbers as follows:

UISFF QMVT UXP TRVBSFE = 21.9.19.6.6 17.13.22.20 21.24.16 20.18.22.2.19.6.5

Then subtract 1 from these numbers:

20.8.18.5.5 16.12.21.19 20.23.15 19.17.21.1.18.5.4

Convert these decreased numbers back into letters:

THREE PLUS TWO SQUARED

The answer to which is of course, SEVEN, which translates to $\boxed{TFWFO}$ .

P/S. The statement at the bottom was meant to be a hint where HINT is the plaintext of IJOU.