Tantras are a series of scriptures, like the Vigyan Bhairav Tantra (the 112 ways of Shiva). These scriptures describe all parts of life as an inner- and outer cosmos.
The study of Shakti Tantra is mostly related to worship of the Feminine Energy, the Goddess in all aspects of life.
God is one and unity (Advaita). Duality is the Maya (illusion) we live in and therefor 1.Shakti is the femine aspect of God and is manifesting continuously with 2. Shiva (Tantra). Shiva is the masculine aspect of God and pure consciousness (static energy).
Shakti is flowing within as Prana or sexual energy (natural life force) and is also known as Kundalini seated on the root chakra.
For me personally the study of Shakti Tantra and the studies of mysteries of the Mahavidhyas (10 Wisom Goddesses) gave me so many revelations that expanded all aspects of life.