my teacher said if i/m a beginner i don't want to choose margin trading because easy to loss money. but if learn enough you can get x2 money
You should be thankful you have a very good teacher bro. Marginal trading is not for newbies and usually I do not even advise anyone who is just starting their trading to go in with real funds in a spot market, let alone when it comes to marginal trading.
Marginal trading exposes you to more risk and as a newbie trader, who wants to gain experience and confidence in your strategy and how to play the market to your advantage, can quickly get frustrated with marginal trading if care is not taken. At least in a spot market you can hold, but in the marginal trading type, once you get liquidated, you are out!