Per IRS Instructions for Schedule K-1 (Form 1065) Partner's Share of Income, Deductions, Credits, etc. (For Partner's Use Only), on page 17 (for Box 20, Code V):

Code V. Unrelated business taxable income. The partnership will report any information you need to figure unrelated business taxable income under section 512(a)(1) (but excluding any modifications required by paragraphs (8) through (15) of section 512(b)) for a partner that is a tax-exempt organization.

TIP: A partner is required to notify the partnership of its tax-exempt status.

Note. This information represents your share of Unrelated Business Taxable Income (UBTI) and is reported for use by not-for-profit organizations. It should be disregarded by individuals.

Per IRS Instructions for Form 1065 U.S. Return of Partnership Income, used when the Partnership does their return (which created the Schedule K-1 they sent you), on page 47:

Unrelated business taxable income (code V). Report any information a partner that is a tax-exempt organization may need to figure its share of unrelated business taxable income under section 512(a)(1) (but excluding any modifications required by paragraphs (8) through (15) of section 512(b)). Partners are required to notify the partnership of their tax-exempt status. See Form 990-T, Exempt Organization Business Income Tax Return, and Pub. 598, Tax on Unrelated Business Income of Exempt Organizations, for more information.

Note that any link in the information above is updated each year automatically and will take you to the most recent version of the document at the time it is accessed.