What is Framing?
The frame of a photo is the background and foreground of a photo that give it depth, dimension and contextual storytelling. To explain framing better, lets look at some examples.

The Frame in action
This photo from Grove City Men's lacrosse is a perfect example of creating your own frame in a photo. Our person of interest or subject is number #22 in the middle. To highlight this player, we have the focus of the camera blurring out the foreground automatically, but we as photographers can use framing as a technique to further highlight our subject.
To frame my subject, I used a gap between other lacrosse players in the huddle who were closer to me to add depth and a second dimension to my photo of #22. Framing a photo is using your surroundings to add depth to a photo that you otherwise couldn't get without a second object.

Can you find the frame of this photo?
If you said the linemen closer to the photo, you'd be right! A common athletic photography practice is utilizing other players to create a frame for your player of interest!
What are the benefits of framing?
Employing this practice can bring a few new details to your photography
- It helps ensure that the subject is the main subject of the image. The frame serves as a boundary that helps maintain the viewer’s focus on the photographer's intended subject of the photo
- It adds depth to your photos. This can bring a flat, 2D photo into a 3rd dimensional realm that gives the audience more things to look at
- The frame can add contextual storytelling to your photo. In my first photo, it would have looked odd If I only got #22 without the other players standing in the middle of the field. Utilizing framing with the other players in the huddle gives the context of the photo.
Find more here
5 Composition Tips for Sports Photography - Lloyd Belcher Visuals
The Importance of Framing in Photography: Techniques and Tips