There are many ways to do this and highly depends on your use-case. I mainly use these three Variations...
1. Public Variable 2. Public Static Variable 3. Public getter/setter Variable
1. Public Variable - make Variable public like this:
Access public Variable from another Class:
or
2. Public Static Variable - they are easily accessible when the Class/Script is applied to the same GameObject. Downside, it's value is not serializable 🙁
3. Public Getter/Setter Variable - So, to make this Variable serializable AND read-only to avoid potential future debug-issues, make it a private setter: