Power BI itself is not a programming language, but a Business Intelligence (BI) tool developed by Microsoft. However, it uses two main languages: DAX and M. DAX, or Data Analysis Expressions, is a formula language used mainly for creating custom calculations in Power BI, Analysis Services, and Power Pivot in Excel. M, also known as Power Query language, is used for data extraction, transformation, and loading (ETL) tasks. These are the primary languages a Power BI developer uses to manipulate and analyze data within the tool. It's also worth noting that knowledge of SQL can be very helpful when working with Power BI, even though it's not a language native to Power BI.