Computer is an electronic machine, that can accept data (input) work and the data according to given command (process) produce result (output) and the store the result for future. It’s called computer.
Hardware - its physical component of a computer system. E.g. Mouse, Monitor, Key Board come under this category. You relate your physical body to computer hardware like eyes, ears etc.
Software: Is a collection of programs, procedures and documentation that will make physical components in computer to do some task. for say Ms Office Windows Xp Paint