If the photo is hosted by pexels.com, then you need to include the fully qualified domain name and not just the image name. There's also a typo in your code (remove the
.> from the end of your image path):
<img src= "https://pexels.com/path/to/file/pexels-photo-134634-1.jpeg" width="250" height="400">
If your photo is on your web host, then double check the path to that image as well. It should be a relative path (relative to the html file that's loading the image).
<img src="/path/to/image/pexels-photo-134634-1.jpeg" width="250" height="400">