Software, or computer software, is a generic term for instructions and/or data that run on a computer.
Software is synonymous with the terms program and application.
Software can describe an operating system like Windows 10 or macOS, or their underlying processes. Software can also describe things like Microsoft Word or Adobe Photoshop.
The term software is often contrasted with hardware.
Computer hardware, is physical or "hard", and is difficult to change once it's produced.
Software runs on computer hardware, and is "soft", or easy to change in comparison to hardware.