Everyone has a worldview. Put simply, it’s how each of us sees the world. What we believe about everything is added to this view, and either matches or mismatches what we already believe. If we can understand another’s worldview, we have a head start on helping them see the truth of the gospel.
A worldview is a person's attempt to combine what they believe is true into a single narrative. There are a number of competing worldviews, but the most common pair in the western world is that of naturalism vs creationism. There are inherent flaws in naturalism that make it unworkable.