If you are logged in to your Ulule account, just click on your profile picture in the top right corner (your profile is displayed on all Ulule pages) and then change the language of the page as well:
You can select French, English, Spanish, Catalan, Italian, Portuguese, German or Dutch.
Please note that the interface is translated but the content of each campaign (and its translation) is managed by the project creator.
Alternatively, you can change the page language from the footer on all Ulule pages in this way: