To export a list of leads/opportunities/customers/contacts/product (or anything else) go to the app you want to export from. For this example we are going to export a lead list:
If you are in Kanban view (card view) click the "Show All" link to see a list of all of your leads. Then click the checkbox to select all of your leads - then click the "Select all ### objects matching" if you'd like to export every lead in your CRM. Note: If you'd like to only export a select group the use the "Search Leads" functionality to narrow down your search based on whatever criteria you'd like.
Once you have all of your leads selected, click the Bulk Action button above your list and select "Export." From here you can select what format you'd like to export the file as, and choose between exporting all fields for each lead, or just the current fields showing in your list:
Once you choose the format, your computer will ask you where you would like to save your file, and you can download it from there.
This works exactly the same in any application within the CRM.