Hello,
I would like to use jovie to read my ebooks. There is no option in the Tools menu to use Speech.
I don't know where to look. I couldn't find anything on my search.
Thank you for your help.

Jovie is not used anymore for Qt5 applications; Qt5 ships a module (Qt Speech) with the same features. Unfortunately the module was not stable until Qt 5.10, so sometimes distributions did not enable it for the applications that supports it.
In this case, the Okular package in Ubuntu 17.10 is not compiled with the Qt Speech support, so there is no much to do. You can try to open a bug against kubuntu packages and ask to have the support enabled. I'm not sure if this can happen for the already released Ubuntu 17.10, but at least it can be fixed for the future Ubuntu 18.04.
Anyway, this is a packaging/distribution problem and there is no much that we can do here on kde.org.