What it does
A plain-language summary is coming. Here is the official summary from the Congressional Research Service:
House Office of Legislative Counsel Modernization Act This act authorizes the designation of more than one attorney in the Office of the Legislative Counsel of the House of Representatives as Deputy Legislative Counsel. (Previously, the law authorized only one deputy.) A Deputy Legislative Counsel must perform the functions of the Legislative Counsel during the Legislative Counsel's disability or absence (including a vacancy in the office).
How Congress voted
This law passed by voice vote or unanimous consent, so there is no record of how individual members voted.