Databases provide access to collections of information such as books, journals, encyclopedias, etc. Some databases provide information in full [text] whilst others will only give the reference and an abstract.
You will need to use them when you research.
The advantage of using databases (rather than Google or Google Scholar) when researching is that you can be assured that the information you retrieve is from a reliable source.
The search box on the library website searches across a large number of databases in one search; however, there are some databases that are not included in the library website.