Provided your site administrator has made the appropriate changes to the site Design Package (see Enabling the multi-language section menu), you will see a menu item, usually near the section menu, that allows you to toggle back and forth between the current page and its translation on the other site. For example, if you have an English and a French site, you will see a link to the French site when you are on the English site and vice versa.
Important points to keep in mind:
If there are more than two sites in the translation set, you will get a drop-down menu when you click on the link.
The links only appear if the linked pages have both been published.
If you emergency publish and break the link to the associated page, the button will not be displayed.