This is more of a question for your database administrators than for Dataiku. So you really should speak with the corresponding administrator of all the data technologies that you connect to in Dataiku. For instance for Microsoft SQL Server you can read this guide. If encryption is not enabed at rest or in transit in any particular data technology you use you will need to configure that data technology backend and the Dataiku connection accordingly.
In terms of Dataiku there are only a couple of things you can do with regards to encryption. One is to enable file system encryption where Dataiku is installed, if you are using File System connections for your data. Finally you should enable HTTPS in Dataiku so that all your traffic between Dataiku and your users is also encrypted.