What does it mean when my text is highlighted pink ??

The applied font is missing.

"InDesign substitutes missing fonts with an available font. When this happens, you can select the text and apply any other available font. Missing fonts for which others have been substituted will appear at the top of the Type > Font menu in a section marked “Missing Fonts.” By default, text formatted with missing fonts appears in pink highlighting."

(http://help.adobe.com/en_US/indesign/cs/using/WSa285fff53dea4f8617383751001ea8cb3f-6e29a.html#WSa285fff53dea4f8617383751001ea8cb3f-6e17a)