Not every item has one
Some items have a minimum order quantity and some do not. Where a minimum applies, it is shown on the item as "Minimum order" together with its unit of measure. An item with no minimum shows "No minimum".
It is a floor, not a step
The minimum is the smallest quantity you can order for that item. You can order any amount at or above it — you do not need to order exact multiples of it.
If your cart rejects a quantity
If you enter a quantity below an item's minimum, that line will not be accepted until you raise the quantity to at least the minimum shown.