There are many trading indicators, and sometimes traders pay money for special indicators that are not publicly available.
TradingView has developed a programming language called "Pine Script" where users can develop their own indicators and upload them to TradingView.
This means that you can find almost any trading indicators in one place and use them for free.
Unlike MetaTrader, where you have to search for indicators on forums or special websites, TradingView keeps all indicators in one place, which will save you a lot of time.