Trailing Stop is an algorithm to manage Stop Loss orders.
Once a trailing stop has been placed (for example, if a trailing stop's value is 15 pips) the following occurs:

How to specifyTrailing Stop level
Note: It is very important to note that no Stop Loss order will be placed until the market moves in your favour, as mentioned above. Therefore to limit losses, a separate Stop Loss would need to be placed manually.
In order to place a trailing stop, highlight the open position in the ‘Trade’ tab of the Terminal window and right-click to open the context menu.