Tx and rx pins

Hey guys, i have a co2 sensor with serial output, can i just plug it into the approprate tx and rx pins on the board to display a readout on the serail monitor?

Not he serial monitor uses those two bits. Use a software serial emulator to read the output from your sensor.

i have a co2 sensor with serial output

You need to check the signalling very carefully before connecting to your Arduino. If the device uses RS232 voltage levels, it could damage your Arduino.