In Vedānta (one major philosophical framework of yoga), Adhiṣṭhāna(m) translates to: seat / basis / ground / support / abode / the substance from which something is made.
This tradition asks us to discriminate (have ‘viveka’) between everything that is unstable due to its nature of change, and that which is beyond change - our underlying essence. That which is the basis or foundation for everything else.
It is a reminder that all of our human concerns & limitations rest on a basis of stability; existence or being itself. In my experience, we can gain insight into this when we sense our own presence in the pauses between mental movement.
This is why meditation is often called a process of ‘remembering’. Relaxing mental busy-ness to remember our essence nature.
In Vajrayana Buddhism the term also means ‘grace’ and ‘blessings’, which makes sense to me; there’s a certain sense of alignment and reciprocity with the universe when our minds return home to quietness and we rest in our natural state.