More about it:
Impressions are used to measure the effectiveness of campaigns, engagement, and popularity of the post, tweet, or advertisement across various social media platforms. It is important to note that an impression does not necessarily mean that the content has been engaged with, just that it has been seen.
On different platforms, if you have a business page, you can see impressions on your post through the insight option.
Below are “impressions” of a post published on Instagram. It shows the impressions as in the view count, which the post got in different ways.