Kali, who represents Time, is the first and foremost of all Shakti-s, i.e. energy forms. Since all of creation manifests and exits in and thru her, she is also a representation of space- where all things can come into being. In this regard Kali represents the Space-Time continuum which allows for this manifested material world to exist.
In a comprehensive understanding of the various primordial energies, called The Ten Great Wisdom Goddesses or Dasha Mahavidyas; Kali is the first Maha Vidya- i.e. the first of the Wisdom Goddesses. The rest of the Mahavidyas represent various aspects of creation and even though they exhibit various forms of the feminine principle of creation, they are all considered as coming forth from the first Mahavidya, which is Kali.
Being a very primordial, potent and foundational energy, Kali is also considered as the ruling energy and presiding deity in all Tantric and Mantric studies, i.e. studies of the Universal Energy of Tantra (Tools of Cosmic Creation & Existence) and Mantra (Power of Sound, Speech & the Spoken Word).
Since Kali is the basis of ‘manifestation’ of this created world from Pure Potentiality of Consciousness (Shiva), she represents the kinetic energy, governs actions and represents the very existentiality of a manifested (i.e. created) form.