A wind gust is a brief peak of wind speed above the 10-minute mean wind. In a METAR it appears after the letter "G": the entry 18012G22KT means a steady wind of 12 knots gusting to 22 knots.
Small drones are destabilised by gusts far more than by steady wind — it is the sudden shove that knocks the aircraft off balance. That is why you must always compare the GUST figure, not the mean, against the wind limit stated by your drone's manufacturer.