Everyone hides from this broiling desert sun,
Tarantula, snake, lizard, and scorpion.
A couplet is two lines, a pair or couple. It brings together two things for a complete thought. Although it doesn't have to be, most couplets are rhyming. The challenge for the poet is to make the brief lines worthy of notice. Basically what a couplet does is notice a moment and to say this matters and this matters.
The animals I list are all from the desert around my house. What animals are around your home? What is the weather or the terrain like? Can you put them together to write your own couplet? Try several of them.