It depends. How many children do you have and what are their ages?
1900 is probably the extra credit you are getting now after you already received 1500. Check 1040 line 19 and 28 and Schedule 8812.
Or it is the total you qualify for including the 1500. So you might have 400 on your return.
@Jamie-conner For a 16 year old child, the child tax credit is $3000. It sounds you received $1500 advanced child tax credit and Turbo Tax is giving you a credit for the remainder. If it shows, $1900, it means you may have another credit somewhere in your tax return for $400.
Go to tax tools>tools>view tax summary in the left pane of your page. Now select preview my 1040 and looks on lines 25-33 to see if there is a $400 credit listed in addition to your $1500 child tax credit. It may possibly be an earned income credit or some other deduction. Check this section also to see if the $1500 credit you are to receive is properly applied in line 28 of the 1040. Also, check to see if there is an entry in line 19 of the 1040.