* kʁwa
Breakdown:
* k: Like the "k" in "kite"
* ʁ: This is a French sound that doesn't exist in English. It's a uvular fricative, similar to a slightly raspier version of a guttural "r". If you can't make the sound, just pronounce it like a regular "r"
* wa: Like the "wa" in "water"
So, the whole word sounds something like: "kroy"
Keep in mind that the "r" sound is important, as it distinguishes "croix" from words like "crois" (meaning "I believe").