Form I-130A, Supplemental Information for Spouse Beneficiary, is a separate supporting form that must be filed along with the marriage-based I-130 petition.
In other words, Form I-130A must be submitted by a petitioner who is filing Form I-130, Petition for Alien Relative, on behalf of his/her spouse. The both forms must be filed to USCIS together. Form I-130A itself should be prepared by a beneficiary, and not by a petitioner. A spouse (beneficiary) who is present in the United States must sign the I-130A. A spouse (beneficiary) who is outside the US must still complete the form, but is not obliged to sign it.
As Form I-130A is required only for the marriage-based green card process, it is not required for filing of I-130 petition for other kinds of family members (children, parents, etc.).