Reading out conductivity sensor through modbus & RS485

Hey everybody!

I'm trying to read out a conductivity sensor through the Modbus protocol and a RS485 connections.
I want to setup the Arduino as my master and the sensor as a slave, so the Arduino will request data from the sensor. It's a Modbus RTU interface.
But I have pretty much no idea what I'm doing, since I never worked with Modbus before.

I'm using an Arduino MKR WiFi 1010 board with the Arduino MKR RS485 shield.
There's a a bunch of libraries for it, but I don't know how to properly use them.

Does anybody have any experience with anything similar and could they help me? Please?

You picked a difficult task for a Newbie. Sorry to tell you but a lot more information is needed to begin to help. What sensor?: Does it have a RS485 interface, if so read its manual so you know how to communicate with it. Take your time and work through each section until you master it. Expect this to take many weeks. I would suggest you get the Arduino cookbook and read that and maybe some of the "Dummies" series of books on the Arduino.

It's a MOSTEC Conductivity sensor Type M3836. The sensor has a Modbus RTU RS485 interface.
While I'm not an expert, I do consider myself familiar with Arduino. The whole RS485 and Modbus part is where I get lost.