how do you monitor traffic?
Using for example the built-in tools “torch”, “packet sniffer” or “Traffic flow”
https://help.mikrotik.com/docs/display/ROS/Packet+Sniffer
https://help.mikrotik.com/docs/display/ROS/Torch
https://help.mikrotik.com/docs/display/ROS/Traffic+flow
For other tools have a look at
https://help.mikrotik.com/docs/display/ROS/Diagnostics%2C+monitoring+and+troubleshooting
If you don’t ask a specific question about what you want to do, your question is open to many interpretations.
Forgot to mention you may also use an external packet sniffer as well for example Wireshark.