Think about chaotic movement, unstable flow of wind… this is what wind turbulence means. If still not clear… remember last time you were on an airplane there was turbulences. Not nice.
Why is so important wind turbulence in any tall construction? Very simple, assume your hands and arms are the wind and a small bar of metal is a crane. Now try to bend it applying continuous force, you will probably bend it (unless the metal bar was too big to start with!) but it is very unlikely that the bar would snap. This is a continuous and steady flow of wind.
Now bend the metal back and forwards, you will see what happens very quickly.. the metal will snap in half (eventually). This is wind turbulence for you, a chaotic pushing and pulling by the wind on any structure and that is what it makes it dangerous.
Some of the windiest places in Scotland for wind turbines (like a crane, very tall structure) where it would be the perfect place for a wind mill, wind turbulence has stop some projects going forward because this chaotic (wind turbulence) flow of wind would eventually break the structure.