Search queries tool provides insights to how people are finding your site on Google.
You can use the filters to really understand if people getting to your site are mainly from image search, web search, mobile search, or video search. You can also filter by region to see form which countries people are finding you.
Check the trend for both impression and clicks to observe any effects that might have caused by you (marketing campaigns, improvements on your site) or external factors (Google algorithm updates, increase in competitors) .
Find out which pages have low Click Through Rate and improve them.