Physical appearance is often a major part of the halo effect. People who are considered attractive tend to be rated higher on other positive traits as well.
However, this effect doesn't just affect our perceptions of people based on their attractiveness. It can also encompass other traits as well. People who are sociable or kind, for example, may also be seen as more likable and intelligent. The halo effect makes it so that perceptions of one quality lead to biased judgments of other qualities.
The term itself uses the analogy of a halo to describe how it can affect perceptions.
When you see someone through the lens of the halo effect, you are seeing them cast in a similar light. That "halo" created by your perception of one characteristic covers them in the same way.