Software is a set of instructions that tell a computer what to do. Just like how you give someone directions to get from one place to another, software gives directions to a computer to perform certain tasks. These tasks can be anything from opening a document, playing a game, or connecting to the internet.
Software development is the process of creating this set of instructions (software) using programming languages. Think of programming languages as a way to communicate with a computer. A programmer uses these languages to write code, which is then compiled into software that the computer can understand and execute.
The process of software development involves several steps, including planning, designing, coding, testing, and debugging. The end goal is to create software that works as intended and meets the needs of its users.
Overall, software is the language that computers speak, and software development is the process of creating that language to perform tasks on a computer.