The montage is a way to show the passage of time. It’s a rapid use of images to show days, weeks, or years passing in the life of your story. In movies you might see calendar pages falling, or a series of newspaper headings, or a tree with the seasons changing from fall to winter to spring.
Here are examples of how to do the same in your writing:
Example: Mary wandered down the street of her home town. In the second hand store window, she spotted an old camp stove, reminding her of the trips she and her husband used to take up to Lake Coeur d’Alene. She entered and poked through bins of faded postcards, shelves of old glassware, toys children had played with and now discarded. In the back she found a rack of old dresses and tried a couple of them on, her image in the mirror bringing a rare smile to her lips. How much she looked like her mother.
A clock bonged and she glanced at her watch. Where had the afternoon gone? She was late.
Example: John planted his garden in early May after the last frost. All spring and summer he enjoyed the fruits of his labor, but before he knew it, he was picking the last of the tomatoes and squash.