Margin Call is a notification which lets you know that you need to deposit more money in your trading account in order to sustain your open trades, or close losing positions, so you free up more margin. It's also widely known as a fixed percentage.
You can learn more about what margin call is in our educational video:
At NAGA you will receive the first warning email, when your margin drops below 100%.
Your trades will start closing when your margin has reached the 50%, starting with the most unprofitable one.