Bleed is a printing term.

Printers cannot print right to the edge of a paper sheet. To create that effect, the printer must use a sheet which is larger than the document size. Then the printer prints beyond the edge of the document size (usually 1/8), then cuts the paper down to the document size.

It is the designer's responsibility to set the bleed correctly. Although 1/8 is standard, different printers have different requirements. Speak to your printer about how much bleed he needs before you design your job. With today's advancements in technology bleed specification can vary form printer to printer. For example the bled standards shown below are common in most commercial print shops and are summed up as 1/8" bleed. We can actually get away with 1/16" bleed, which can save even more money when deal with bulk business card order

Click Here to View Video on Setting up Bleed Properly