Delphi
In plain terms
A rapid application development tool built on the Object Pascal language.
Going deeper
Delphi pairs Object Pascal with a visual designer to build native Windows (and cross-platform) desktop apps quickly. It had a strong following for business software.
Under the hood
Compiles to fast native code with a component-based VCL framework; still maintained for legacy and cross-platform native apps.
Examples
Windows desktop business apps, point-of-sale systems, legacy enterprise tools.
Think of it like...
Like a prefab construction system: snap together components to raise a sturdy app fast.