kon-soo-MAH-toom est
Here's a breakdown:
* kon: Like the beginning of "cone"
* soo: Like "sue"
* MAH: Like "ma" in "mama"
* toom: Like "tomb"
* est: Like "est" in "best"
The stress falls on the second syllable, "MAH".
It's a Latin phrase meaning "It is finished" or "It is accomplished." It's famously associated with Jesus' words on the cross.