In Curiosity, autocomplete refers to the act of the application offering suggestions to the User as they type in the search bar.
By default, the application will suggest token values that it looks like the User may be typing (token values are nouns that are encountered when the system indexes text content, see Natural Language Processing for an overview of this process).
You may mark fields on other node types to appear as autocomplete suggestions.
To do this, either click on the Curiosity menu button and then Settings and then Search and then Autocomplete (this is a convenient way to add fields from multiple node types) or if you're already in the Data Hub, and looking at a node type, then click Autocomplete in the sidebar. In either view, you will now see fields that are already enabled for autocomplete and you can click + Add more to extend this list.
Select the field(s) that you want to be used as autocomplete suggestions and click Accept.
As when configuring fields for use in Full Text Searching (see the Ranking section in that article), individual fields can be made be suggested a better or worse autocomplete suggestion by changing its boost multiplier (the [+] and [-] buttons at the end of each row) -
The values in the field(s) that you have added will now* be presented if they match the text being entered into the search box -
* (Sometimes there will be a short processing delay but often it is immediate)