Why should I learn PowerShell?

PowerShell is a cross-platform shell and scripting language that's required for managing Windows servers, and is capable of managing the cloud, including Linux and Windows, Azure, AWS and GCP. If you want to automate something, PowerShell is both a task-based command-line shell, and a powerful scripting language -- with full access to the .Net Framework. It's also the standard for managing Windows Server and other Microsoft server products and services.

If you need more, Warren Frame and Don Jones wrote a short eBook on the subject. Why PowerShell?