The floor function ⌊x⌋ rounds x down to the nearest integer. For example, ⌊7.9⌋=7 and ⌊−2.3⌋=−3 (down means toward negative infinity).
Integer division is floor division for positive numbers. When you compute ⌊7/3⌋, you get 2, the same as integer division.
Watch out for negative numbers. ⌊−7/3⌋=⌊−2.333...⌋=−3, not −2. Different languages handle this differently, so check the documentation.