Reading the result
The four boxes show the version needed at levels L, M, Q and H. If the level you want pushes the version up a lot, shorten the content: a short link, capital-letter-only text, or dropping tracking parameters all help.
In practice
Uppercase URLs are legal and scan the same, and the alphanumeric mode they allow is 25% more compact than mixed case. HTTPS://GETQRSTUDIO.APP fits in a smaller version than https://getqrstudio.app. Most people prefer the look of lowercase, so weigh it against the size gain.
▸The four encoding modes
Numeric mode packs 3 digits into 10 bits. Alphanumeric mode (digits, capitals, space and $%*+-./:) packs 2 characters into 11 bits. Byte mode uses 8 bits per byte, with UTF-8 for anything outside Latin-1. Kanji mode packs Shift JIS characters into 13 bits. Encoders may switch modes mid-string to save space. The encoding explainer walks through it.
Try it yourself
Take the version from here into the size calculator to find out how big the code must be printed.