Eunice here from the Shopify team. Thanks for posting!
Are you looking to buy in bulk and hold the stock yourself, or are you looking to dropship?
Dropshipping is a retail fulfillment method where a store doesn’t keep the products it sells in stock. Instead, when a store sells a product using the dropshipping model, it purchases the item from a third party and has it shipped directly to the customer. As a result, the seller doesn’t have to handle the product directly.
If you're looking to buy in bulk there are plenty of suppliers on Alibaba that ship globally. But, if you're looking to dropship, the Shopify App Store is the place to go to install dropshipping apps, such as Oberlo. Oberlo connects you to Ali-Express suppliers, most of whom ship globally.
What is it that you're looking to sell?