It's in the instructions.

"In column (d), check the type of contribution. Check all that apply for the contributor listed. If a cash contribution came directly from a contributor (other than through payroll deduction), check the “Person” box. A cash contribution includes contributions paid by cash, credit card, check, money order, electronic fund or wire transfer, and other charges against funds on deposit at a financial institution.
If an employee’s cash contribution was forwarded by an employer (indirect contribution), check the “Payroll” box. If an employer withholds contributions from employees’ pay and periodically gives them to the organization, report only the employer’s name and address or “N/A,” as applicable, and the total amount given unless you know that a particular employee gave enough to be listed separately.
Check the “Noncash” box in column (d) for any contribution of property other than cash during the tax year, and complete Part II of this schedule."