In Power BI, What is RELATED function

DAX formulas can leverage the full power of
the model you already have, including relationships between different tables that already exist.

We can apply DAX expressions the new column
For example,
I have "ProductCategory" table and "ProductSubCategory" table

Data table fields:

Data OutPut:

DAX Formula:

ProductFullCategory = RELATED(ProductCategory[ProductCategory])& " - " &[ProductSubcategory]

from above expression, RELATED is the dax function which will join two columns.
ProductFullCategory is the column created in ProductSubCategory table with DAX function.
Inside Related function, we have to specify which table we need the columns and its column name.