Most forms of writing involve description. In a short story, characters and places need to feel real for the reader. Description of events, feelings and atmosphere helps to achieve this.
There are a number of ideas and skills you can use to improve the quality of description in your writing. Using interesting words can help to stop writing becoming dull and flat.
The first words that occur are not always the most interesting that could be used, for example
"really". It can help to think about what specific verbs and adjectives apply to the situation.
"We had a really nice dinner," could become,
"We enjoyed a tasty meal" or
"the children had a great time at the circus" could change to
"the children shared a thrilling night at the circus".
Variety makes writing interesting but remember adjectives are only one way of improving descriptions. Careful choice of verbs can help too.