I mean the article explains exactly what he meant:

"A bipartisan bill would be good for America and help fix our broken immigration system and allow speedy access for those who deserve to be here, and Congress needs to get it done,” Biden said. “It’ll also give me as president, the emergency authority to shut down the border until it could get back under control. If that bill were the law today, I’d shut down the border right now and fix it quickly.”

The deal being negotiated in Congress would require the U.S. to shutter the border if roughly 5,000 migrants cross illegally on any given day.