Count common value

[Boivin12]

I have a list of people and a list of team number.
Every person is attached to one singe team but its name appear several times (I made a simple table).
I would like to know how many people there are in a team (3 in team 1 and 1 in team 2 in my example).
I know it's not a big deal but I can't wrap my head around it...

Person ID	Team number
A	1
A	1
A	1
B	2
B	2
C	1
C	1
C	1
D	1

 

[Boivin12]

Clear all cells in col C & then re-enter the formula in C2 only.

Still, it gives me the same thing, I don't know if it has an impact but, I have some blank cells in my column 2. Here's what I entered, I don't think that there are issues =MAP([Column2];LAMBDA(m;ROWS(UNIQUE(FILTER([Column1];[Column2]=m)))))

 

[Fluff]

You cannot use spill ranges in a table, so use

=ROWS(UNIQUE(FILTER([Column1],[Column2]=[@Column2])))