315 MHz transmitter + Wi-Fi

You can’t use the sketch as is with an Uno as you only have 1 serial port, unlike Mega or Leonardo that has several.

Alter the following part to look like this:

// Hardware Serial on Mega, Leonardo, Micro...
//#define EspSerial Serial

// or Software Serial on Uno, Nano...
#include <SoftwareSerial.h>
SoftwareSerial EspSerial(2, 3); // RX, TX

Connect ESP-01 rx to pin 3 (TX) on Uno and ESP-01 tx to pin 2 (RX). If it doesn’t work try swapping the pins around.

BUT your Uno is a 5V device whereas the ESP-01 is a 3.3V device so you need to ensure you drop the voltage from the Uno TX to the ESP BEFORE you do anymore testing if you haven’t already done so.

I thought I made that sketch so that it would use SoftwareSerial for debug, to prevent instability with the ESP and have the ESP to the hardwire. Thing to remind though, when you upload, disconnect the ESP! Connect it after you loaded your sketch and reset the Uno with the button.

Did you select the right board in the Arduino IDE? If it says blynk.cloud you are using an old library I think. it should be blynk-cloud.com to which you connect. Have you got the latest 0.3.7 library installed for Blynk?