How to make a page that has posts inside?

A category archive is already this kind of “page”. All you need is to add new menu item to a custom top menu. Also you can strip category from a category archive url by plugin WP No Category Base.
If you want to have special page template for it, read article about custom page templates.

ok thanks i kind of understood that response. real noob here! but thanks !

In other words – you already have this page. If you have “blog” category –
it will have address yoursite.com/category/blog
Just add a menu item with this link and (optionally) strip category from url.
Of course there are much more possible customisations of theme, but this is basic way.

Another way is to find a theme that already has a “blog” page template.

thank you ??