The joint resolution S. J. RES. 61 proposes that Congress disapprove a rule submitted by the Federal Highway Administration. This rule concerns the "National Performance Management Measures; Assessing Performance of the National Highway System, Greenhouse Gas Emissions...
Simple Explanation
S. J. RES. 61 is about Congress saying "no" to a new rule that would check how much pollution comes from big roads. By making this rule go away, they are stopping it from happening.