Just to dumb down what @Bitcoin_Arena have said, the suffix "m" indicates the type of account you are going to use in order to execute a trade of a particular trading pair -- which in this case is associated with "
Standard Account"[1].
In other words, it's just regular trading account that has access to any type of asset with no commission fee as described ny their article.
[1]
https://www.exness.com/standard-accounts/