In English: to live - living (Living on Earth): to cook - cooking (Title: Cooking of vegetables). I am specially interested in a substantival form for "Speaking"
In French, the infinitive is the substantivated form of a verb so you can say:
Living on earch → Vivre sur Terre.
Cooking of vegetables → Cuisiner les légumes.
Speaking Spanish → Parler l'espagnol.
You might also use regular nouns:
La vie sur terre.
La cuisine des légumes.
La langue (parlée) espagnole
in the latter case, langue is often omitted:
Some infinitives can be used as real substantives, which is the case of parler so a (rarer) alternative is:
Le parler espagnol.
There is also the very outdated parlure:
La parlure espagnole.