Lists allow you to store data in the form of a row consisting of a pair of data - a unique, single key and specific information corresponding to the column type in which they are located. Construction of the list is similar to the construction of a typical dictionary in which the information is found based on the unique key.
Country list, with columns: Name(key), Currency(Text)
SysUser list, system list columns: Email(Key), Name(Text), IsActive(Boolean)...
Read more about creating new lists in this article.