If selected then tones will follow the spoken Chinese, that is if two third tones appear consecutively the first syllable will be modified to show the second tone.
As an example, if selected then nǐ hǎo will be presented in the way it is really spoken that is as: ní hǎo
This setting only affects the website and is not used in the dictionary or lists of the apps (but will be applied to newly created flashcards)