A hand job is the sexual practice of masturbating a man by hand. This normally refers to another person using their hand but can refer to the man masturbating himself.
Because it is the easiest form of access to a man's penis, using the hand is how many people start, either on themselves or on a male partner.
This is a "hand job" using one's feet. In Japanese, this is referred to as ashikoki.
With care, it may be done in public under a table covered with a large tablecloth. Someone with sufficiently agile feet can even undo the trouser zip and extricate the penis with their feet.