Making summary of sentences

The general approach would be

$ awk '{ count[$2]++ }
       END {
           for (name in count)
               printf("%s signed %d time(s)\n", name, count[name])
       }' <file
Harold signed 1 time(s)
Dan signed 1 time(s)
Sebastian signed 1 time(s)
Suzie signed 4 time(s)
Jordan signed 2 time(s)
Suzan signed 1 time(s)

I.e., use an associative array/hash to store the number of times that a particular name is seen. In the END block, iterate over all the names and print out the summary for each.

For slightly nicer formatting, change the %s placeholder in the printf() call to something like %-10s to reserve 10 characters for the names (left-justified).

$ awk '{ count[$2]++ }
       END {
           for (name in count)
               printf("%-10s signed %d time(s)\n", name, count[name])
       }' <file
Harold     signed 1 time(s)
Dan        signed 1 time(s)
Sebastian  signed 1 time(s)
Suzie      signed 4 time(s)
Jordan     signed 2 time(s)
Suzan      signed 1 time(s)

More fiddling around with the output (because I'm bored):

$ awk '{ count[$2]++ }
       END {
           for (name in count)
               printf("%-10s signed %d time%s\n", name, count[name],
                      count[name] > 1 ? "s" : "" )
       }' <file
Harold     signed 1 time
Dan        signed 1 time
Sebastian  signed 1 time
Suzie      signed 4 times
Jordan     signed 2 times
Suzan      signed 1 time

While awk is using an associated array and that would be limited to the memory size you have, you could do as the following instead:

sort -k2,2 infile | uniq -c

Or to do formatting as you want:

sort -k2,2 infile  |uniq -c |awk '{ print $3, "signed", $1, "time(s)" }'

This job is for awk. You need an array[index] to do it:

awk 'NF {name[$2]++} END{for (each in name) {print each " signed " name[each] " time(s)"}}' file

Jordan signed 2 time(s)
Dan signed 1 time(s)
Suzie signed 4 time(s)
Suzan signed 1 time(s)
Sebastian signed 1 time(s)
Harold signed 1 time(s)

NF is to remove extra blank lines. The data is stored in the index and value of the array. Values are referenced with the corresponding index.