This is called "income in respect of a decedent." See publication 559. You report it and pay taxes on it because you are the person who is entitled to receive it after your spouse's death.
https://www.irs.gov/publications/p559
You would not file a joint return, because your spouse was not alive in 2023. You will file as single (or maybe as qualifying surviving spouse, if you have dependents) and you include the income as if it was your own.
If your spouse was being paid a disability income on a W-2, but the checks were paid in the year after he died, the employer or insurance company should not have issued a W-2 and should not have withheld social security and medicare tax (box 4 and 6 on the W-2). The income should have been reported on a 1099-MISC with no taxes withheld.
In a perfect world, you would contact the payer to get the W-2 canceled and re-issued as a 1099-MISC. If they withheld social security and medicare, they should refund that. (SS and Medicare is sometimes withheld from disability but not always.). At the very least, you should contact them and request that they do this, give them a fair chance to respond, and keep copies of your correspondence. Because, if they refuse and you report the income differently (but correctly) the IRS may send you a letter, and it will be easier to explain the situation to the IRS if you can show that you asked for the correction and they refused.
If you want to file without contacting the payer, I can tell you how to do that, but I would recommend you ask them first.
