Sat-Chit-Ananda is a Sanskrit term and refers to the nature of the core of our Being or Self. Self is only One Whole. However, it is expressed through the conditioned mind in three ways.
Sat means Existence.
Chit means Consciousness.
Ananda means Bliss.
In Advaita, the very nature of the Self is defined as Sat-Chit-Ananda. In Nirvikalpa Samadhi, Self is experienced as a simultaneous mass of Bliss and Consciousness, whose very nature is that of Existence.
The term Sat-Chit-Ananda cannot be fully understood without direct experience of the Self. The mind can end up simply wrestling with it self about such things. What is needed is to go within and abide in one’s essential being. After that it makes perfect sense.