A slash (/) is a punctuation mark used for various purposes. Other names for it are: stroke, virgule, diagonal, right-leaning stroke, oblique dash, solidus, slant, separatrix, slake and whack, forward slash. A mark in the reverse direction (\) is called a reverse slash or backslash.
Example: to show how many kilograms of barley are left out of your total supply of barley; 155/2000.
A slash can also be interpreted as "and". For example, "He is enrolling in the JD/MBA program at Harvard". It can also be interpreted as "or". For example, "Each employee must bring his/her Photo ID". There, the slash (/) means "or".