|Encryption essentially scrambles data using a special key. By using the same key the data can be recovered to it's original form. But without the key it is very difficult to recover the data. With NTFS encryption the key is a part of the user account so encryption and decryption are totally transparent to the user. When accessing the files you may not even be aware they are encrypted. But to a different account the data is inaccessible.|
It is possible, but very difficult, to break NTFS encryption. I mean a great deal of time by an expert on a powerful computer. Unless the data is of great value to someone else it just isn't worth the effort.
But be aware that NTFS encryption has it's disadvantages which you should be aware of, particularly if you wish to use it in a business environment. There are other types of encryption and they all have their strengths and weaknesses.
Do an internet search if you need more information.