Off-balance" stands for "off-balance sheet." Off-balancing of owned real estate is generally one of the financial methods used by companies to separate the ownership and use of real estate, and to reduce the risks and liabilities of owning assets.
As a typical example, a company raises funds from investors and financial institutions, establishes a special purpose company to purchase some of the real estate it owns, sells it to that company for resale profit, and then separates it from its balance sheet.
After the sale to the special purpose company or an unrelated real estate investment company or real estate investment fund, etc, the company may continue to lease back the property as a lessee.