My taste buds on the tip of my tongue are turning brown what does that mean ?

Staining?: Coffee drinker? Smoker? Dipping? Staining of the tongue can be caused by these items. Your post did not elaborate.

Benign self limiting: It is caused by build up of keratin on the taste buds.It can also be caused by smoking or hot beverages and best itreatment is to use tongue cleaner or scraperon a daily basis which will remove the keratin layer.