Hi Kelly048,
Yes, you certainly can import customers, suppliers and employees. Customers and suppliers can be imported from Outlook, Gmail or as an Excel spreadsheet and you can find detailed instructions here. This page also answers common questions on importing data to QuickBooks Online.
Importing employees can be done using an Excel spreadsheet - see here for detailed steps on this process. You can also import your Chart of Accounts, products and services, invoices, bills, and historical bank data.
-Kass
