Display a line for. hit(s) per second

It is possible to display a line on a visualization for each hit per second.

On the Discover tab there are total 12 hits, divided in 2 seconds
Between 12:00:00 and 12:00:01 there are 8 hits.
Between 12:00:01 and 12:00:02 there are 4 hits.

How can I visualize this?

Yes, this is possible. Create a new line chart visualization, then under "buckets" select "X-Axis", and under "Aggregation" select "Date Histogram", then under "Interval" select "Second". Hope this helps!

Yeah, got it.
Is it possible to display the average in a Metric?

In this case the average would be 6.

Unfortunately, that won't be possible until the following is implemented: