Thanks for providing the information. I have inspected your site and tried the search. Most of the results were coming from the pages. By default, pages do not have any excerpt which is why the very first 30 words were taken from the page content. If you have inserted a slider, most probably the slider codes were the one that is displayed. You can prevent this from happening by inserting a page excerpt. This will require a little customization though.
Pages are usually used as the landing page, where the post is for blog articles and that’s what separates them. And the theme will adhere to the default standard provided by WordPress. It still doable, but again, would require customization. Example,
https://www.wpbeginner.com/plugins/add-excerpts-to-your-pages-in-wordpress/ (for adding excerpt support for Pages).
https://www.wpbeginner.com/beginners-guide/how-to-add-featured-image-or-post-thumbnails-in-wordpress/ ( for adding featured image support for Pages)
Once you have modified and added the page excerpt, you will need to edit each of the respective pages and insert a manual excerpt or the excerpt that you want to display in the search results. Manual Excerpts are optional hand-crafted summaries of your page content that can be used in your theme search results.