Yes, you need to know coding/programming to use Upstox API.
As far as the programming language, it all depends on your requirement.
Every language has its own merits and demerits over others.
If you want to execute a simple breakout price action strategy on nifty 50 or any number of stocks with predefined target and stoploss,you can just do it with Excel/VBA.
Learning programming is very hard if you don't have interest but it is very easy if you have interest to learn.
Choosing the right language is the first and crucial step towards algorithmic trading.