Plain English Meaning
It is a paper or digital map made for pilots flying by visual reference. It shows what is on the ground, where airports are, what the airspace looks like, and what to avoid — at a scale that gives a useful view of a region.
Full Definition
A VFR sectional is an aeronautical chart published by the FAA at a scale of 1:500,000, designed for pilots flying under Visual Flight Rules. It depicts terrain elevation, airports, airspace boundaries and classes, navigation aids, communication frequencies, obstructions, and visual landmarks used for pilotage. Sectionals are named after a major city in the area they cover (e.g., Los Angeles Sectional, Seattle Sectional) and are updated on a regular cycle.