Returning Member

Does my 19 year old College Student actually need to file a return for 2018

I have filled tax in USA married jointly and My wife was working in India she did not stay in USA more than a month, I have given tax on her India income in India and in USA, I want to understand do i need to pay tax in both the countries or If I will pay in India then no need to pay in USA? If I paid in bith the countries tax on her Indian Income can I get refunded that amount in USA?

2- What does means to declare spise world wide income if filling married jointly? Declaring means I ha e pay to pax in USA or if I paid tax on her income in India then only I have to declare in USA but no need to pay tax in USA, is it true statement?