Hi @Viji ,
To do this, you'll need to have a common value across the rows in which Paxata can "Group" the rows by. So giving a very simple example where you have a single column of values, you'd use a "computed column" to add a "constant" value. In my case, i have added the letter "a":

Once you have this, use the "Shape" to "Group By" as below (i am showing here two different calculations here
average/mean and
median: