I search the connections of a spindle encoder and find nothing. Thanks for your help

Please post a link to the board details then someone might be able to help.

Well if you look at the FAQ you will find this:

This controller does not have an encoder input to determine the speed of a lathe spindle. The Pokeys57CNC does have an available encoder input.
https://www.buildyourcnc.com/item/electronicsAndMotors-electronic-component-breakout-Mach4-mach3-USB-ethernet-Board

Click the link to add information to this solution:
[575] how do i connect a lathe spindle speed encoder to this usb breakout board controller so i can set up for thread cutting on my lathe and on the mill for threading

The board does support spindle speed control but clearly not closed loop since you cannot connect either an index pulse or encoder.