Start with the meaning
Wind speed describes wind over the averaging period used by the provider. A gust is a brief increase, so it is a separate value rather than an amount to add to the wind speed. Definitions and averaging periods depend on the weather product. The National Weather Service also defines wind direction as the direction the wind comes from.
Read one hour carefully
For an illustrative forecast of 10 km/h wind and 18 km/h gusts, keep both values in view. Do not add them to make 28 km/h. Compare the same unit, time and height with the guidance for your specific aircraft. A number alone cannot settle whether the conditions suit your flight.
Look through the vertical profile
In Drone Forecast, the Premium Wind screen compares 10, 80, 120 and 180 metres. Select the period you need and compare the displayed directions and speeds. These are forecast levels, not permission to fly at that height or measurements of the air around your aircraft.
Recheck at the site
Refresh the forecast before departure. At the location, compare what you observe with the forecast and reassess your plan when they differ. Use the aircraft manual and current local information; this guide does not provide a universal wind limit.