The natural, physical world & Universe: It includes the properties & rules of the Universe, some of which is known, some of which is unclear or unknown.
True, mainstream science is based on the systematic study of the natural world as opposed to naturalism, the belief that there is nothing outside of nature. True science does not claim to know everything. The scientific method is in fact, a rigorous ongoing process, intended to weed out any false conclusions. It is always subject to revision by any new information that truly conflicts with an existing theory. However, a number of scientific theories have been repeatedly proven and can be relied, such as in electricity, vehicles, planes, computers, space vehicles, engineering, medicine, etc.
Culture, Worldview, Politics
Science is influenced by people who have a particular culture which can influence their beliefs. They can have beliefs which are not science, such as Naturalism, the belief that all truth is in the natural world, which is not supported (or contradicted) by science. Analytical philosopher Alvin Plantinga argues strongly in Where the Conflict Really Lies that naturalism conflicts with evolution or New Atheism which go beyond science to opinion. Other descriptions of areas that go beyond true science are: materialism, the belief that only matter, it’s movements and modifications exists; and scientism, the belief that science is the only authoritative worldview to the exclusion of other world views, atheism, and religious beliefs (surveys say that 30% believe in God and identify with a Christian religious group). These and many other beliefs are beyond true science in that they cannot be proven by the scientific method. That does not necessarily mean that they are incompatible with mainstream science. Some beliefs are, some are not.
More information on New Atheism, Richard Dawkins, “The God Delusion,” and others, plus a rebuttal in:
Why Science Does Not Disprove God – Amir Aczel, Ph.D, secular science writer, Time 4/27/2014