It's a very common root, and many English words are derived from it, including:
* Vocal: Relating to the voice
* Vocabulary: A set of words known by a person or group
* Vocation: A strong feeling of suitability for a particular career or activity
* Advocate: To publicly support or recommend a particular cause or policy
* Invoke: To call upon (a deity, spirit, etc.) for help or protection
* Evoke: To bring or recall (a feeling, memory, or image) into the conscious mind
* Provoke: To stimulate or give rise to (a reaction or emotion, typically a strong or unwelcome one)
Understanding this root can help you better understand the meaning of many English words.