In Japanese, hizamakura 膝枕 means "lap pillow." This is when someone offers their lap as a pillow to someone else, so they lay their head on there.
The word hiza 膝 generally means "knee," the body part, so hizamakura sounds like a "knee pillow." The area above the knee is what you'd call the lap in English.
The term hizamakura also refers to a product that's an actual pillow shaped in the form of (presumably) a woman's lap. (seriously.) This kind of product is similar to a dakimakura 抱き枕, which would be a "hug pillow" instead.
