It stands for unrestricted retained earnings; it represents a part of retained earnings (RE)- i.e., of total retained earnings, that are available for distribution to shareholders/ equity holders, as dividends, without any restrictions such as those imposed by regulators or covenants (creditor protection covenants), or contractual obligations, etc. Technically, unrestricted retained earnings reflect, on the asset-side, the amount of net assets that an entity can, legally or contractually, release as dividends (distributed profits) and hence will be removed from its statement of financial position (SFP) and accounting records.
In a corresponding context, URE may also be used as acronym for unappropriated retained earnings.
