This means to imagine how the subject appeals to your senses- how does it smell, looks like and so on.
Unlike argumentative essays, you’re not required to add the responses of others; instead, describe a place, person, situation, an object, or emotion, etc. The key is to make use of sensory details: smells, sights, sounds, touches and tastes to enable the reader to form a picture of what the writer is trying to describe. Using the right vocabulary, adjectives and adverbs, sensory details, and figurative language is fundamental to a compelling descriptive essay.
The purpose of a descriptive essay is simple: describe a person, place, thing, or event in a heavily detailed manner to form an exact picture or deliver a specific impression in the reader's mind.
Hence a descriptive essay plays with at least one of our five senses (touch, smell, taste, hearing, sight).
In other words, the description of the person, place or thing in an essay should be really vivid.