A collection is a kind of page which you can create on Wikiversity to better organise your contributions or your teaching. It is one of many resource types which you can create here. There are two main kinds of collection - but you may think of more.
Collections which coordinate content development 
An author or group of authors may find it convenient to create a page which simply organises whatever content they happen to be creating. A single author might also use their User page for this purpose, but a group of authors may find a page in the "main namespace" (i.e. normal area of Wikiversity) more convenient. Sometimes the Topic namespace can be used if the pages fall under an identifiable "topic", but if you cannot find a suitable "topic" name and you just want a page which coordinates what you or your project team are creating, you can create a "collection" page.
Collections which coordinate learning 
A "learning collection" is a listing of resources intended for a particular real world audience. It is comparable to an Amazon reading list. For example, you may have a particular class and you may wish to have a single URL where you send them on Wikiversity - but once they get to that URL, they may need to split up into different directions. The learning collection might consist of learning resources which you have created yourself, but it could also list resources which others have created. The collection's content is determined by what its particular audience needs.
Creating a collections page 
Choose any title you like and create the page. Then add some links to the pages which you are "collecting" together in the collection. Please tag the collection with [[Category:collections]] to identify it as a collection.
See also 
Activities: Simulations - Games - Labs - Experiments - Challenges
Miscellaneous resources: Experimental resources