What are Search Targets and Search Query Input in seomatic?
This has to do with Google Structured Data and how your site appears in search results. If you use these fields, your site will show a custom search box in Google Search results, like this:



Basically, the Search Target is a URL where you'd want any search queries to get directed to. So in the example above for Pinterest and a custom search for "Pizza", the Search Target might be:

pinterest.com/search?q={search_term_string}


The Search Query Input basically just tells Google what the placeholder is that you used in the Search Target. So in our example it would be:

search_term_string


I'd recommend reading this 
page from the Google Search docs in order to better understand what Search Targets and the Search Query Input are.