Upside means facing upwards or looking at things from a new angle.
Imagine you're building a house and you start with the foundation. When it's time to install windows, they have to face the outside of the house – that's when we say they're on the upside of the building. But "upside" is also used in a more figurative way. For example, if someone says their job is on the downside, but then finds out they get a promotion and it's actually on the upside, they'll be happier. People might say something is on the upside when it's good news or an advantage.
The highest or uppermost side or portion of something.
