Automating products

Hello. I work for a veterinary e-commerce site and I have to add manually a lot of products but it's very time consuming.

80% of the products we sell are bought from another website. How can I add products from that site directly to mine and also have the same stock like them?

I heard that I can ask them for an excel with all products but are there also wordpress plugins that can work for me?

Thanks a lot for your time