I dont't understand button (Try to control the sg90 servo motor through the nodemcu)

And yet you still didn’t properly format it as per the Welcome Topic :wink: (so I did it for you).

Reading things like that and the Documentation will show you how to do what you ask about.

Blynk%20-%20FTFC

http://help.blynk.cc/getting-started-library-auth-token-code-examples/blynk-basics/keep-your-void-loop-clean

http://help.blynk.cc/getting-started-library-auth-token-code-examples/blynk-basics/how-to-control-anything-with-blynk-app

BLYNK_WRITE(vPin) {  // Use Button/Switch Widget set to a corresponding vPin
  if (param.asInt() == 1) {  // If button state is 1 or HIGH
    // Run START motor code (don't block... use timed functions)
  } else {  // If button state is 0 or LOW (or actually anything else then the prior option)
    // Run STOP motor code
  }
}