Your brokerage statement shows the foreign income and the passive income.Enter those numbers from the statement.

The 1116 is giving you credit for taxes paid to a foreign country. The IRS wants to know how much you made in which countries. A zero for income does not make sense. You would not pay taxes on zero income.

Are you sure that putting in income is right?  The form is asking for "adjusted basis of investment assets generating foreign income," not the income.  Note that this is in the section relating to interest expenses.  I have zero interest expense so it seems the assets generating income should not matter.