You can save time and keep on top of new research by setting alerts. Various databases and search engines offer alert services for you to set up. You can create an alert to run on a specific search query (ie. your research topic), or track specific authors or publications that you follow.
A citation index is a database that tracks citations between article, books, and other works. Some offer the functionality of creating reports based on your search query, or for specific works. This is also where we get some research metrics from, like impact factor and h-index. Refer to this guide for more information about citation analysis. For any given index, any associated metrics are only for the works included in the index. This means a journal may have a different impact factor in Google Scholar than in Web of Science.