In short, if you use Nginx and PHP-FPM (aka FastCGI Process Manager) to run PHP – which can in the right hands be a blazing fast configuration – then PHP workers is synonymous with the number apportioned to
The number of workers, multiplied by the amount of
Determines the amount of concurrency your system can handle, for example:
Could in theory handle 1024 concurrent connections.
For PHP applications, you should generally have as many workers as you have CPU cores.