Excel trending data based on dates & other information.

Gonzo45  NOTE: I converted your tables to be "Formatted as a Table" because this well be easier to read and expands as the table expands.

Try this formula but there are many variations you can use.

=SWITCH(LET(c,COUNTIFS(Table1[Accident Date],$I$2,Table1[Accident Class],"A",Table1[Accident Type],$B$1)-COUNTIFS(Table1[Accident Date],EDATE($I$2,-12),Table1[Accident Class],"A",Table1[Accident Type],$B$1),
IF(c<>0,c/ABS(c),0)),
1,"↑",
0,"↔",
-1,"↓")

so what I do is first COUNTIFS for conditions for TODAY and the - COUNTIFS for 1 year ago (I used EDATE( today, -12) to get same date 12 months ago)

now you could use a couple of IF statements but I chose to check if it is 0 or if not then divide by ABS value of itself to get a positive (1) or negative (-1) output and then use SWITCH for 1, 0, -1

That all said, it gives your text arrows as the output but NOT color formatting.  Color formatting must be done using Conditional Formatting.  That said, there is a conditional formatting option to use Icon Sets that would get you really close to what you want without that whole SWITCH and ABS() business.  Just return the value like this:

=COUNTIFS(Table1[Accident Date],$I$2,Table1[Accident Class],"A",Table1[Accident Type],$B$1)-COUNTIFS(Table1[Accident Date],EDATE($I$2,-12),Table1[Accident Class],"A",Table1[Accident Type],$B$1)

and use conditional formatting as shown here:

and make sure to click that box that says "Show Icon Only"

this is also in the attached file