Question about brick mortar

Some friends recently moved into a house they are going to buy and close on in Oct. Meanwhile they have discovered some places in the brick mortar look like the mortar has turned to sand. There are holes in the mortar and it can be raked out by the finger. Anyone here have any ideas what would cause that problem and how to fix it.

It's not unusual. Mortar is pretty largely sand, anyway, and if water gets in it and freezes, it will get crumbly. The brick will need to be "re-pointed," which is scraping out the bad mortar, putting new mortar in, and being sure it is recessed between the bricks so it resists moisture.