which programming language use in PLC? which language you will prefer for plc programming and why?
Ladder logic is by far the most common. If you are interested in learning the basics, here are a couple of links to help with your decision:
https://www.watelectronics.com/how-to-program-the-programmable-logic-controllers/
https://www.dosupply.com/tech/2018/09/10/differences-between-plc-programming-languages/