This bill extended federal government funding through May 5, 2017. It was enacted on the day funding was to end. The federal government is currently funded through "continuing appropriations" legislation that maintains government spending levels as they were for arbitrary periods of time. Traditionally, though not recently, the federal government was funded by major funding legislation for a whole fiscal year at a time. If an appropriations law is not enacted before the last one lapses, non-critical federal government functions shut down.
The summary below was written by the Congressional Research Service, which is a nonpartisan division of the Library of Congress, and was published on Apr 29, 2017.
(This measure has not been amended since it was introduced. The summary of that version is repeated here.)
This joint resolution amends the Continuing Appropriations Act, 2017 to provide continuing FY2017 appropriations for most federal agencies through the earlier of May 5, 2017, or the enactment of the applicable appropriations legislation.
It is commonly referred to as a continuing resolution (CR) and prevents a partial government shutdown that would otherwise occur after the existing CR expires on April 28, 2017, because 11 of the 12 FY2017 regular appropriations bills that fund the federal government have not been enacted. (The Military Construction, Veterans Affairs, and Related Agencies Appropriations Act, 2017 was signed into law on September 29, 2016.)
The CR also amends the Surface Mining Control and Reclamation Act of 1977 to extend through May 5, 2017, a provision that provides health care benefits for certain retired miners and their families.