One thing you can try is going into the page’s Edit mode, by pressing “Edit” on that page, and then checking whether that text is by any chance the actual excerpt. If you can’t see an “excerpt” section on that page you can go to the top of that page, click “Screen Options” on the top right, and tick the option “Excerpt” (see image).
If you find that the excerpt of the page is actually empty, meaning that your theme is probably generating a predefined excerpt when no excerpt is present, you can download your theme to your pc and do an in-file search using the text it is generating (in your case “Lorem ipsum …”). This way you can find out where it is in your theme’s code that the text has been hard-coded.
You can use some software like AstroGrep in order to perform the search.
