The grey frame on the screen is a "bleed area" of about 4 mm, where we cut the cards in the production process.
Trim: the final size of the printed products is referred to as the trim size.
Bleed: this is the area outside of the trim line that will get cut off. Even though it ultimately gets removed it’s still important for the production of your product.
If you have a photo which goes up to the edge of the card, this "bleed" should be covered by your photo. This prevents a white line appearing between the photo and card edge, as we cannot predict exactly where the cut in this 4 mm area will be (it's a mechanical process).
Be careful not to include any text in this area as it is likely to be cut off.
Safe Zone: this is the area between the trim line and safe zone line where any text, important parts of photos, logos and other critical parts of your design should be kept outside.