We are married in 2006,filling jointly with one son, 11 years old, as dependent, why I have $0 in my exemption amount? The exemption amount in 2017 is $12150.

Personal expemptions and dependent exemptions were eliminated entirely starting in 2018. However, the standard deduction has doubled. So you are getting a $24K standard deduction since you're filing joint.

Personal exemptions were eliminated by the new tax law.  Now you have a higher standard deduction instead.  Your standard deduction lowers the amount of income you are taxed on.

Your standard deduction lowers your taxable income.  It is not a refund 

2018 Standard Deductions:

Single   $12,000  (+ $1600 65 or older)

Married Filing Separately    $12,000  (+ $1300 65 or older)

Married Filing Jointly  $24,000  (+ $1300 each spouse 65 or older)

Head of Household  $18,000  (+ $1600 65 or older

Look at line 8 of your Form 1040 to see your standard or itemized deductions.

https://ttlc.intuit.com/questions/4482394-how-will-tax-reform-affect-my-2018-federal-tax-return