Clarification sought.... "Cover your long/short positions"

While practicing on a trading simulator Tradingsim ,I saw that it had 4 buttons…Buy,Sell,Short and Cover. Kite/Pi have only Buy and Sell.

  1. If that platform already has a 'Sell button,what is the need for the ‘Short’ button.
  2. What purpose will the ‘Cover’ button accomplish…I want to know what does ‘Covering a Long or Short position’ exactly mean ?
  3. Why can’t we have a ‘Basket’ order on kite/pi , Which accepts both long (MKT& SL/SLM order for buy above CMP and Limit order for target)and short (MKT & SL/SLM for sell below CMP and its corresponding Limit target order)positions on a stock.If the long portion of the order is triggered,then both the opposing short and its corresponding target orders should get cancelled.