"How so?" is an English equivalent of the French phrase Comment ça? The question translates literally as "How that?" in English. The pronunciation will be "kuh-maw sa" in French.
Comment? in French is "How?" in English.
"How?" in English is Comment? in French.
"How are you?" in English is Comment allez-vous? in French.
Comment est-il? in French means "How is he/it?" in English.
Comment est votre...? in French means "How is your...?" in English.
Comment tu fais? in French means "How do you do it?" in English.
Comment t'appelles-tu? in French means "What are you called?" or "What is your name?" in English.
Je suis comment? in French means "How am I?" or "What do I look like?" in English.
Comment dit-on en français? in French is "How does one say in French?" in English.
"How do you spell it?" in English is Comment s'ecrit-il?in French.
Comment ça va? in French means "How are you?" in English.
"How was school?" in English means Comment était l'école?in French.