Physicalism is itself a philosophical point of view about the mass and energy in which humans exist and of which the Universe is made. It used to be called materialism. People exist within the field that is the Universe as it is generally understood. People tend to believe it is made of particles and waves that are energy. The entire structure from largest to smallest isn’t fully known, though a lot of the things within it are. Some believe God created and sustains the energy field-as it could all be within his thought, others think it might be a hologram or even pure mathematics at its core, yet one thing can be certain; people experience the Universe.
Physicalism is also known as material monism. Some people use the concept to distinguishing if from Ryle kinds of ghost-in-the-machine theories about spirit. Personally I believe God needs no extra substance for a soul to be immortal. If a soul is information God as an omniscient being has no loss of information as if Shannon entropy destroyed His data. Actually information is thought never to be lost from the Universe-even at a black hole. So with the right information God can sustain or clone a soul (though each is unique in theology) and give it whatever span he chooses. What is information to absolute Spirit one might wonder?
Physicalists tend to be monists exclusively, though lacking an overall account of everything that is falsifiable (obviously and perhaps necessarily)
The Universe could as well be an idea, or a super-computer simulation.
https://plato.stanford.edu/entries/berkeley/ Berkeley’s ideaism
https://physics.aps.org/articles/v6/111 The Higgs Field
https://arxiv.org/abs/0704.0646 The Mathematical Universe