Generally speaking, you wouldn’t normally want to insert a post into a page. Most often, when someone asks this question, they’re really asking how to add a “page” that displays all their blog posts. That’s not exactly how WordPress works.
To accomplish this specific task, you’ll simply want to create an Archive page, then name it, “Blog” or whatever you like. Finally, you can link to this archive page in your site’s navigation menu. Then, whenever someone clicks the link to your blog archive page, they’ll see a page that displays ALL your blog posts, in chronological order.
BUT, you may have a specific use case that calls for a blog post to be inserted into a page. One easy way to do this is to simply copy the URL (or Permalink) to the post you wish to insert into your page. Then, paste the URL into your page where you want the post to appear, and WordPress will automatically embed a snippet that represents the blog post.
Finally, you may want to display a grid of blog posts in a page. This video by our good friend, Kori Ashton, demonstrates one way to do that:
If you’d like to explain in more detail precisely what you’re trying to accomplish, I’ll do my best to provide more specific guidance for your particular case.
Hope this helps!