As a single owner LLC, ordinary income is any pay you receive from clients or customers. You may receive income reported on 1099-misc box 7, which you should enter as such. Any other income you receive that's not reported on a form, should be entered under general income.
For other tax calculations, you may be asked about "ordinary income" and this would simply be all the income your self-employed LLC business received during the year (total sales/payments).