You apparently have a dependent, and are filing Married Filing Joint. With that filing status the standard deduction for 2017 is $12,700 and the self-exemption for each married couple is $4050 meaning together you get an $8100 self-exemption for the two of you.

Then your first dependent gets you another $4050 exemption bringing that total from $8100 to $12,150. If you had a 2nd dependent, that would raise the exemption amount another $4050 to $16,200.

If you have two dependents, then either one of them does not qualify to be claimed by you as a dependent, or you made an incorrect selection or entry in the program, thus telling the program you do not qualify to claim that 2nd dependent.