
Explanation

The SharePoint Migration Tool lets you migrate content to SharePoint Online and OneDrive from the following locations:
* SharePoint Server 2013
* SharePoint Server 2010
* Network and local file shares
The first step is to create new SharePoint sites in SharePoint online. These sites will host the document libraries which will host the migrated content.
The second step is to create the document libraries in the SharePoint sites to host the migrated content.
The final step is to use the SharePoint Migration Tool to migrate the content.
Reference:
https://docs.microsoft.com/en-us/sharepointmigration/how-to-use-the-sharepoint-migration-tool