We're marry. at the time been we're currently living abroad, just thinking in the future.
You mean you were married at the time your son was born? Then the "5 years, including 2 years after turning 14" requirement that SusieQQQ is the right one, and your wife probably didn't meet it at the time your son was born. You would have to add up the duration of all the trips she made to the US after she turned 14 to see if it adds up to 2 years. (On the other hand, if your son had been born out of wedlock, the requirement would have been 1 continuous year of physical presence, which your wife would have met.)
If your wife didn't meet the requirement to pass citizenship to your son at birth, the way to get US citizenship for your son depends on whether your family is planning to move to the US or remain residing abroad. If you plan to move to the US, your wife would petition your son to immigrate (i.e. become a US permanent resident); when your son enters the US on the immigrant visa, he will immediately become a US permanent resident, and also immediately become a US citizen under INA 320, as a permanent resident under 18 living in the US with a US citizen parent. The petitioner must be domiciled in the US in order for the beneficiary to immigrate; that's why this route is only if you are moving to the US.
If your family plans to remain residing abroad, you can get naturalization for your son through the INA 322 process. Your wife would file N-600K, and she would need to show that her US citizen parent (your son's grandparent) had been physically present in the US for "5 years, including 2 years after turning 14" up until now. When they approve it they will call your son to go to the US for an interview and take the oath. Your son would need to enter the US as a nonimmigrant, usually as a B2 or VWP visitor, to attend the interview and take the oath. Entering the US as a visitor requires that there be no immigrant intent; that's why this route is only if you are not moving to the US.
