So, we're going to blend these two tables into one so we can display Ads impressions next to Analytics sessions at the country level in the same table (and if we wanted, we could then create calculate fields).
To do so, please click in the top menu on Resource, Manage Blends, and then Add a Blend. For Table 1, I'll choose the GA4 connector (that I'll rename GA4 by clicking on (Table Name)). I'm going to choose Country as a dimension, and sessions a metric.
Then, click on Join another table, choose your second table (in my case, the Google Ads sample data that I'll rename GAds). I'll add again Country/Territory as a dimension and impressions a metric. At this stage I know that Country from first table and Country/Territory from second table are the same type as they've got the same little world icon left to their names. Often, blend breaks because dimension types mismatch.
If you followed my steps, you should see that: