Yes. If he received his residency status in 2020, you need ro include his income, if married filing joint,  The resident aliens and US citizens must report worldwide income on their income tax return.  

What form do we fill out in order to do that. He didn’t receive any tax form from his employer outside the US.

it depends. 

If your husband was an employee you can use Form W2 in TurboTax to report the information related to your husband's foreign income.  Fill in as many boxes as you have information for and leave the rest blank.   

If your husband was self-employed, he can report the income using Schedule C and deduct any ordinary and necessary expenses he had related to that income.