Bleeds and Safe zones are guidelines to ensure your design prints optimally.
The red outline on the design, called the Safe Zone allows you to visualize the area that will not be trimmed during the printing process. Any elements placed within this safe zone will remain intact and uncut after printing. Make sure no text goes beyond this line or it may be cutoff in printing.
The blue outline indicates the bleed zone or extended edge for printing. To ensure that your photos and design elements extend to the edge after it is printed and trimmed, make sure to extend any elements, especially photos, to reach into the blue outline and to the very last edge of the design canvas.