You need a debugger - IDA is fine. Start an emulator or connect your device via adb command. There are guides online (this part is tracing)
Breakpoints are for tracing purposes. It basically links functions up. For example, a correct breakpoint triggered while coins are incremented will inevitably lead to the actual increment code.
Guides regarding setting breakpoints are readily available, eg. reverse engineering stack exchange.
BUT... Your function name is obfuscated, There could be hundreds of thousands of methods & functions within assembly.csharp. If you want to go down this path, be prepared to spend alot of time.
Maybe try asset file hack - some game store textassets in the obb or assets/bin folder as UnityFS - UABE can dump and compile these, and sometimes it just work. Or do a save hack - some simpler game don't have save encryption, only saved in root directory - which (I think) can be bundled with an .apk.