Answer: The act placed a limit on the president's ability to send troops into hostile areas.
Context/detail:
Passed in 1973 over the veto of President Richard Nixon, the War Powers Resolution (its official name) blocks presidents from continuing the pursuance of a war without Congress's approval. In practice, however, the War Powers Act has often been sidestepped by presidents. The US Constitution leaves some tension in place between the legislative and executive branch when it comes to the country's involvement in war. Article I of the Constitution gives Congress the power to declare war. But Article II names the President the Commander-in-Chief, and presidents frequently have understood that role as containing the authority to deploy US forces without first getting congressional approval. The War Powers Act has been an ongoing point of controversy as US forces have been sent into all sorts of conflict zones in the 21st century without formal declarations of war.