Sometimes in some companies the architect role is not so well defined (at least in my experience) I would like to know which you think are the main tasks of a software architects.
I agree. Too many architects spend too much time coding and not enough on architecture. Main real world tasks are to architect solution that handles current requirements and is adaptable to change.
Need to read read read and build lots of POC's
Does the Oracle Architect certification provides a good overview and deep knowledge over the Java architecture? or something else could be added?
Its OK; not sure about depth. That comes w experience.