Blog posts glitch is showing multiple posts on post instead of only blog page

Can someone help me resolve this issue? I purchased the Wein theme by FreshFace and cannot get my blog to work properly. The blog page shows the posts correctly, however, when you click on a single post and it takes you to the dedicated post page all the posts show up on the post page. I am not a coder so I have no idea how to fix it. Any advice would be helpful.

Blog Page:

Example of Post Page showing all the blog posts when it should be showing only one dedicated post: