Power Platform is the low-code application development and automation platform from Microsoft corporation which can be used with legacy Dynamics 365 and Azure application.
Power Platform is the collective name given to 4 applications: Power Apps, Power Automate, Power Bi and Power Virtual Agents.
Power Platform allows you to create business applications without writing any piece of code ( using PowerApps) and perform automation tasks among Microsoft and third party applications using simple automation tasks or flow ( using Power Automate).
Power BI allows you to create beautiful reports that give you deeper insights into your business data and using Power Virtual Agents you can create bots that respond to your client queries on your behalf.