Agree with @PowerAddict , @365CornerDawid said.
You can use Filter, First or other formula to select one row from your data source.
And another question is how you will show the data, with what compoent? if you don't use gellary, you should choose others, like data table, label.
For example, if I have a data source(Vacation Data), a list from SharePoint, it contains many columns: name, AvailableLeaves, TotalLeaves.
And I can add a Label control, the text property equals: First('Vacation Data').AvailableLeaves
It will show the data value of AvailableLeaves field, in the first row.
Or you can use a datatable control to render the data, set the Items property to First('Vacation Data')
You need 2 steps:
1. select the row you prefered from the data source
2. choose the control to show the data