Does your business operate out of different regions, meaning you have clients who have different preferred languages?
Dynamic content can be used to send out different types of the same communication dependant on which language the recipient prefers.
As shown in the article linked above, a Custom Field for language preferences must be created in either a Free Text or Multiple Choice type. I'd recommend to create a Multiple Choice type, as it'll be quicker when assigning a language to a contact.
When you've created the Custom Field, you'll need to head to your Campaign and setup your Dynamic Content tags.
Once in the tag editor, there are three areas you'll need to be aware of.
Title - Here I'd recommend to split it up into sections i.e subject line, header or body etc
Default Content - This is the content that will be populated in the Campaign if you send to a recipient who doesn't have a field selected
Conditions - Conditions work in the same way as they do in actions, you can set content to appear dependant on the Field, Match and Value.
For language, all content can be added into one tag via the conditions, this way insures all content will trigger in one place and you get just the one default content.
Repeat the same steps with each content area and once completed, you can insert the tags into the Campaign.
Move on to Recipients (making sure you've either selected languages for all, or imported them with data to fill the field with data) and in the Preview and Send stage you can preview the Campaign to see how it will look in the inbox.
When you're happy with the end result and have thoroughly tested your Campaign, you can send out to your Recipients and reporting for each version will appear in the same place.