tr(text) method, like this:
This will automatically look up the key
HELLO when the project starts, and translate it to the user's language (if found in the localization table).
If you need to perform replacements in the translated text, you can do something like this:
For this to work, your translation text will have to contain a text that matches the
%1. Note that
%1 is just an example, you could use anything instead, it should probably be unique in each string though.