Something is laden if it carrying a load. The mule in the picture is laden. A similar word to laden is burdened.
The larval stage of a creature's development is its earliest stage. Many insects have a larval stage, and the larvae can look very different to the adult of the same insect.
Someone is lazy if they don't want to do anything, and so do very little instead. A similar word to lazy is idle.
Someone is literate if they can read and write. Someone who cannot read or write is called illiterate.
Something is long if it goes for a considerable way in one direction. Something goes for a long time if it happens for an extended period. The lizard in the picture has a very long tail. The opposite of long is short.