Actually I can't see it in the list view, it only appears "activity duration" and "initially planned hours". I thought there was a way to calculate remaining hours through this screen, hitting "Calculate network" for example:

http://imgur.com/a/JeL0O

Or maybe there is a way to enable a column on tasks list, how can I do that?

If you list all tasks in list view (not in Kanban)), you can see the used and remaining hours in the listing.