Odoo Community, Enterprise or Online all export the same way. The database backup is the one drop that needs no per-module work; a module-by-module export is there if you would rather bring things across in stages.
The database backup, in one drop
In Odoo, Settings → General Settings → Manage Databases → Backup, download the zip, and drop the WHOLE zip on the Pick screen. Contacts, the chart of accounts, products, customer invoices and vendor bills are read directly off the backup, no manual export per module needed. Payments and journal entries are not read from the zip yet; bring them across the way below.
Or one module at a time
Contacts → select all → Action → Export (include External ID) as CSV or XLSX. Inventory → Products → Export. Accounting → Configuration → Chart of Accounts → Export. Accounting → Customer Invoices, Vendor Bills → Export with lines for transactions, where your Odoo edition supports it. Accounting → Customer Payments, Vendor Payments → Export, and Accounting → Journal Items → Export. These are the two the backup drop above does not carry.
What comes across today
Parties, items, your chart of accounts with opening balances, invoices, bills, payments and journals, the same masters and documents every spreadsheet-shaped source brings.
What is deliberately not copied
Filed GST returns, IRNs and e-way bills stay with the portal that issued them. Bank-statement matches and attached files are not copied either, and neither are Odoo's analytic plans or its posted-state audit trail. That trail is Odoo's own record of who posted what and when, not a figure your books need carried forward.
After you drop the file
The same five screens follow as for every other source: matching columns, a dry run with a verdict on every record, then Import and Reconcile. The mechanics (and how undo and re-imports work) are in Import your data from Zoho, Odoo, Vyapar or a spreadsheet. Back to the full list of sources.