How to convert 2.8kws to wattage

If by "kws" you mean "Kw", or kilowatts, you times it by one thousand.

Kilo is the metric term for thousand. Just like deka is ten, and mega is million.
Deci is tenth, centi is hundredth, milli is thousandth and so on.

2.8Kw = 2,800 watts

Sorry guys, the abbreviation for killowatts is kW. W is capitalized because it is a proper name. KWs is Killo-Watt-seconds which is a unit of energy like killowatt hours. You can't convert kWs to Watts, but as stanfortyman said you can convert kW to Watts as suggested.

Move the decimal place to the left, 3 places.