Bull float
A wide flat blade on a long handle, pushed and pulled across a freshly screeded slab to knock down ridges, fill voids, and embed coarse aggregate.
What does bull float mean?
Bull floating immediately follows screeding and closes the surface enough to protect it while bleeding occurs. Overworking with a bull float brings excess paste and water to the top, which weakens the surface, so the goal is the minimum passes that produce a uniform plane. On air-entrained concrete, restraint at this stage matters because sealing the surface prematurely traps bleed water and air.
In practice
The long-handled aluminum or magnesium float you see swept across a fresh slab in one continuous arc is doing this job.