I need to know if there is some module or something like that in Hybris to create a blog or I need to create a wordpress in subdomain(Bad idea because the web actually is a subdomain xd)?
Unfortunately there is no OOTB Hybris Blog Engine. Utilizing only OOTB you can build a blog using Content Pages. So for example you can create a content page which will represent a particular blog article, also you can create a new component which can fetch all Blog Content Pages and display them in the chronological order.
Based on my experience building a custom blog platform on the top of Hybris is not the best idea. So usually clients are implementing Blog using a wordpress as a blog engine. The integration between hybris and wordpress is usually done through Wordpress REST API. Articles can be fetched from the wordpress instance and displayed on hybris site without having a separate subdomain.