The Text language dialog allows you to specify the language for selected piece of text. While you're typing the text in My Notes Center, the language is set automatically, but if you've copied it from other source, the language may be set incorrectly.

The text language property is important for Spell Checker. The checker determines what dictionary to use while checking the spelling of current word with the language property.

The languages that has spelling dictionaries installed are marked with in language list.