It's not gibberish, it's an Id, which is the type of data Salesforce stores for all Lookup or Master Detail relationships. If you want a linked name, you will need something more like the below. I would change the var to assignment to be less confusing.
You can actually just switch from outputText to outputField because you are using a reference Id. But if you are doing this using a record's own Id, you may need to construct the linked name yourself, which would look like:
<apex:outputLink value="{!$Action.User.View, user.Id}">
{!user.Name}
</apex:outputLink>