Incomplete localization of `{{ entry.postDate.diff(now)|duration }}`
Because neither Craft (nor Yii) provides a default Dutch translation for the word "and".

https://github.com/craftcms/cms/tree/develop/src/translations

https://github.com/yiisoft/yii2/tree/master/framework/messages

You can provide your own translations using Craft's static translations feature, though: https://docs.craftcms.com/v3/static-translations.html