what does "disable linked styles mean"

The concept of linked styles was added as a means to easily apply heading formatting to the beginning of a paragraph and still have Word recognize it for the purpose of TOC creation (I don't remember when the term "linked" was introduced, though). When you make use of this feature (what I refer to as "painting" the formatting of a paragraph style), a special character style, linked to the paragraph style, is created by Word.

The side-effect of linked styles turned out to be that the additional character styles quickly accumulated to create a formatting mess with documents, and the first fix was the option to hide these "char" styles from view. More recently, in Word 2007, the option to prevent the use of linked styles was added.

To answer your direct question, yes, I would recommend selecting the "Disable Linked Styles" option.