Show all entries from an entry field
The elementCriteriaModel is a class/object that handles your search. It's a class that combines multiple methods to fetch entries from your database with an iterable interface on it.

That means: when you receive an entry you get all the queries you need attached to it to pull all the relationship instead of loading all the other entries all the time. So entry.matrix is nothing but database command to pull the other entries which makes craft fast. Otherwise you would take much more time.

To make it short: when you loop through your elementCriteriaModel the method .find() is executed, that fetches all your entries and return them as an array. The method first() returns only the first element, last() returns only the last element.

In order to pull all you just need to loop block.page
{% for entry in block.page %} will to it