In this sell order, what do the values under Trailing and Limit Offset mean? Means it will lag the market by the value in 'Trailing', but what is this limit offset?
The trailing stop limit order is explained on the Questrade web site:
Example: if you place a trailing-stop limit order to buy XYZ shares currently trading at $20 per share with a 5% trailing value and a $0.10 limit offset, this will set the stop price at $21 [$20 (current price) + ($20*5% trailing)]. If the price of XYZ shares increases to $21 per share, a limit order to buy the shares at $21.10 [$21 (stop price) + $0.10 offset] will be sent. If the price of XYZ shares falls below $20 per share, the stop price will continuously adjust to be 5% greater than the current price. So, if the price of XYZ shares falls to $15 per share, the stop price will then be set to $15.75 [$15 (current price) + $15*5% (trailing)].
They also have a video that walks you through the exact trailing stop limit order screen in your image.