Trump for several weeks has said he can live with a steel slat fence instead of the concrete border wall he campaigned on, and the bill as submitted will give him up to $1.375 billion worth of steel slat fence. While that's short of the $5.7 billion he wanted, it's more than the $1 House Speaker Nancy Pelosi was willing to give, and Republicans were calling it a " down payment" on the project.
That down payment is described in Section 230 of the bill, which says $1.375 billion is reserved for "the construction of primary pedestrian fencing, including levee pedestrian fencing, in the Rio Grande Valley Sector."
According to lawmakers, that language will let Trump build up to 55 miles of new border barrier as long as it's a barrier design that has already been deployed there. Since steel slat fencing is already in use at the border, Trump is free to use more of it.
But the bill also includes language that puts a limit on where Trump can build. Section 231 says none of the money can be used to build fencing in five key wildlife areas.