An article has a translation marked in red because the translation has not been updated after making changes to the master version of the article. It would turn green once you mark the translation as "up to date". 

Please navigate to the Solutions tab -> click on the category -> open the particular article in the folder and Click on Edit to make changes to the article. 

Within the article, kindly choose the respective translation (as it is outdated, it would be highlighted in red) -> click on Mark This Translation as Up-to-date on the top right corner of the page. Upon saving this, the article status or the translation icon would be available in green.