Old wax stripped back, fresh coats laid down and buffed to a shine that holds up to traffic.
Floors that have gone dull and grey are usually not worn out, they are just carrying years of old wax and traffic. Stripping takes all of that back off, down to the tile, so the new finish has something clean to bond to.
From there it is fresh coats of finish laid evenly and given time to cure, then buffed up. Done properly it changes how the whole room reads, and it protects the tile underneath from the traffic that would otherwise wear it down.
Most of this work gets scheduled after hours or over a weekend, so nobody is walking on a wet floor during business hours.