How do I add spell checking languages to Pluma?

[orschiro]

Pluma is the default text editor.

To add a spell checking language, install the respective aspell package.

For example, to add German, install aspell-de.

Now you can select a different language from the menu by going to Tools > Set Language.

[Wimpy]

Does using Ubuntu MATE Welcome to install Language Support achieve the same result?

[orschiro]

Assuming you're referring to this screen, then yes, it does. However, it does install a lot more packages: