A load is a bundle of stuff that has to be carried. You might spend your days hauling loads of hay into a barn and your evenings dragging loads of dirty clothes into the laundry room.
Loads need to be picked up and hauled somewhere, like a load of firewood in a pickup truck or a load of supplies in a hiker's backpack. There are figurative loads too — the responsibility, hardship, or worry that you carry around with you: "Her teaching load is light, which is good because her sick cat is a heavy load on her mind." As a verb, load means "fill," like when you load your lunch box with Twinkies.