The review means that your return is pending because IRS is verifying information on your tax return.
You can contact The Taxpayer Advocate Service which is an independent organization within the IRS and is your voice at the IRS.
According to the IRS website, a number of distinct factors can trigger a review, including the need to verify the following entries on your return:
Income is not overstated or understated.
Tax withholding amounts are correct [especially if your employer failed to remit them to the IRS].
You have the right to claim the tax credits on your return.
Social Security benefits withholding amounts are correct.
Household help is accurately reported.
Schedule C income is not overstated or understated.
Or your return may have been selected at random for a review.