1. It is a business intelligence tool which
• analyze data
• clean data
• visualize data that means convert data into a visual format.
Then we can create different reports and different dashboards.
So this is a business intelligence tool.

2. In other languages we define as, Power BI is a collection of following components:
a) Power Query : It is a ETL tool which extracts, transfers, and load the data or we can say it is a cleaning data.

b) Power Pivot : It is represents data modelling. We have multiple data sources, if we want to connect then we have to build a relationship and for that we have to create a model.

c) Power View : In this context, we will perform visualization. Here 250+ types of charts we can do for presentation, reports, dashboards.

d) Power BI Service : After data cleaning, modelling and visualization, we can share among all across world. It helps to communicate with user. Hence we can say it is a package of full components like Power Query, Power Pivot, Power View and Power BI Service.