The Arduino Uno has only one serial port, and you appear to be using this for both the connection to the ESP8266 and your serial debug messages. You can’t do this.
The way to do this with an Uno is to use the SoftwareSerial library to create a second serial port which is used to talk to the ESP (keeping the onboard serial port for debugging, as it has a built-in serial to USB adapter which plugs directly into your PC).
However, SoftwareSerial ports can’t operate reliably at the sort of speeds that you are currently trying to talk to the ESP in your sketch. 9600 baud is the recommended speed to use, and you’ll need to configure the ESP (via an AT command) to use the same baud rate.
A better solution, as has already been suggested, is to throw your current hardware in the bin and use a NodeMCU or Wemos D1 Mini instead…
Pete.