Navigate to Configuration > Database Admin and then select the Data Export tab. On the first tab, 'Orders Export', you can specify various criteria of the orders you require exported, and then hit the export button on the toolbar above the page. A file download dialog should appear, allowing you to save the file. You may need to allow several minutes to download the file if you're exporting a large amount of data.

You can choose to export orders between certain dates or certain order ID numbers.

The field delimiter is the character that will be used in the exported file to separate data. In 'CSV' (comma-separated values) this will be a comma, but you can override this.

The string delimiter is the character that will surround string (text) values in the exported data. The default is a single-quote, but if you find some of the data columns are misformatted when you open in Excel or another program, you can try overriding this.