I am French too and I am trying to understand how you pronounced "hour" before (my dog, cat and wife are already looking at me suspiciously).
You pronounced the "h" like in "hot"? (with the "h" making actually a sound?). I am quite surprised because we do not pronounce and "h" when it starts a word (usually at least), and I've been learning English in the 80's with Brian and Jenny (kudos to the ones who had the same manual) and it was not taught that way either.
In English you almost always pronounce an H at the start of the word. In fact I can't think of any examples other than Hour for when you don't pronounce it
As a native (American) English speaker I would never write or say "an hotel" and I don't think most people would. I confess I didn't realize this was even a debate. An hotel is apparently an older English grammar rule that it appears is considered largely obsolete.
ADDED: You do see a remnant of this with "an historical" but even that is generally not preferred in most dialects. https://www.alphadictionary.com/articles/drgw007.html Basically, it has to do with whether the initial "h" is pronounced in a given dialect of English.
You pronounced the "h" like in "hot"? (with the "h" making actually a sound?). I am quite surprised because we do not pronounce and "h" when it starts a word (usually at least), and I've been learning English in the 80's with Brian and Jenny (kudos to the ones who had the same manual) and it was not taught that way either.