Learn French: Le garçon est très surpris. - The boy is very surprised.

That hook is called a cedilla (cédille). In French, the letter 'c' followed by 'a', 'o', or 'u' usually makes a hard 'k' sound. Adding the cedilla changes it to a soft 's' sound. So, garçon is pronounced 'gar-sohn', not 'gar-kohn'.

What would the sentence look like if it was a girl who was surprised?

It would be La fille est très surprise. You have to change the noun to la fille (the girl) and add an -e to the adjective surpris to make it feminine (surprise). Also, when you add the -e, the 's' at the end of surprise is no longer silent—it sounds like a 'z'.

How do you pronounce est très? Do you pronounce the 't' in est?

No, the 't' in est remains silent here. The verb est (is) is pronounced 'eh'. Because the next word, très (very), starts with a consonant, we do not make a liaison (a linked sound). You just say 'eh treh'.

Since this lesson is about question words, how would I use qui to ask who is surprised?

To ask 'Who is very surprised?', you use the question word qui (who). Because qui is the subject of the sentence, it simply takes the place of Le garçon, giving you the question: Qui est très surpris ?