Household income is the modified adjusted gross income of you, your spouse (if filing jointly), and any dependents who are required to file a tax return. Most times, modified adjusted gross income is the same as total income.
However, more correctly, it's the adjusted gross income from the tax return plus any excludible foreign earned income and tax-exempt interest received during the taxable year.
The household income figure is used to determine if you have to pay a "penalty" on the Affordable Care Act.