Etsy doesn't have a way to bulk upload listings, but you can create one listing and copy it to save time.
Copying creates a brand new listing with all of the info from the copied listing in place. From there, you can tweak and publish.
If your shop isn't open to the public yet
Create your first listing, and then go to the Stock your shop step and click Copy below the item picture.
If your shop is open
Go to Shop Manager > Listings. Find the listing and select Copy from the gear menu.
If you want to copy a sold listing, you can also go to Shop Manager > Orders & Shipping.
You can also copy from one of your public listing pages. A set of Listing Tools links will be at the top of the page for you when signed in. Click Copy.
After clicking Copy from either of these methods, you'll be taken to what looks like the Edit mode for a listing.
This is the copy of your listing and not the original.
You can make changes as necessary. Click Publish when you're done.
The new listing will have a new URL (web address), no views, and no admirers.