If you wish to drive a private vehicle or rental car in the U.S., you must have a valid driver's license. If you have a valid driver's license in your home country, you may use that same license to legally drive in the U.S. However, if any part of your license is NOT in English you are strongly advised to apply for and receive an International Driving Permit (IDP) which is simply an English translation of your current valid driver's license.
Note: If your current valid driver's license uses some English, ALL information must be in English including your name in order to use it legally in the U.S.; an International Driving Permit (IDP) cannot be obtained in the U.S.
If you do not have a valid driver's license in your home country or are not able to obtain an International Driving Permit (IDP) before leaving for the U.S. and wish to drive while in the U.S., the process to gain a valid New York State driver's license takes a minimum of 6-8 weeks at best.