Excellent question and thank you for being part of the Visa Developer Community! I'd love to get you started with Visa payment methods. Please check our website for specific APIs relevant to your business case - https://developer.visa.com/
Particularly, please navigate towards our Payment Methods section using the link below to see all the APIs that fit your use case. I'd like to make the process easier for you too and have included some useful links to APIs that provide payment services, so feel free to take a look.
Also, for commonly asked questions and answers, you can always do a search using the Visa Developer Community forum to see what you can find via this link or search for keywords that relate to the Visa API of your interest - https://community.developer.visa.com/t5/forums/recentpostspage/post-type/thread/category-id/Discussi...
Documentation > API Docs > Payment Methods
Visa Checkout Documentation