u l g i o w y m s m u e b x g z g e n t<
(Note that dot sizes and distances are not part of the puzzle.)
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The answer is:
Dots in groups of 7 (2 + 3 + 2 vertical dots) represent a 7-segment digital display (e.g. 8 = all dots red, 9 = lower left gray, etc.).
Hence the bottom message reads 2539 which we need to substitute with corresponding letters of alphabet to get beci.
This in turn is a key for Vigenère cipher to turn the encrypted text into "theansweriswaterfall".