How does the two income marriage deduction work?

Hello,

could someone please explain in detail what the two income marriage deduction is? While doing our taxes the following came up:

Allocate Federal Amounts to my husband (what does that even mean?)

Taxable State Refunds - Total $0 - husband (with a blank space to enter $ amount)

Child and Dependent Care Expenses -  Total $3,000 - husband (with a blank space to enter $ amount)

 

I am not sure what to enter, or should I even enter anything or leave blank and move on with the automatically calculated dollar amount of $1,200 on the previous page regarding the two income marriage deduction?

 

Any insight would be super helpful - thank you!