This summary is not the rule. The rule text controls.
If you win a court judgment and want to collect money someone owes you by garnishing their wages or bank account, you have to file the garnishment in the right parish court. Which parish is "right" depends on what type of legal action you're using.
If you're using a writ of fieri facias (the standard tool for collecting on a judgment), you must file the garnishment in the parish where the garnishee could be sued. The garnishee is the third party holding the debtor's money or property, like their employer or bank. This is based on the general rules for where someone can be sued, or the specific rule for suing on a debt owed to someone else.
If you're using a writ of attachment or sequestration instead, and the person who owes you money lives in Louisiana, the rule is more flexible. In that case, you can file the garnishment in any parish where you could sue that person directly. This gives you more options for where to bring the case when you're trying to freeze or seize property before or during a lawsuit, rather than after you've already won a judgment.