Yes I just got the 1444 B letter for the 2nd Stimulus payment. It's just confirming they sent it to you. Did you get the first Stimulus payment too? You should have received a 1444 A letter for that one.
You need to enter it to see if you qualify for any more and so Turbo Tax doesn't give it to you again. The Stimulus Checks are really based on your 2020 return we are filing in 2021. So any amount you already got will be reconciled on your 2020 return line 30. If you didn't get a Stimulus Check (and qualify) or you qualify for more it will be added to your 2020 return. But the good news is if they paid you too much they won't take it back.