Learn French: Il met un appât sur l'hameçon.

No, it does not. For the irregular verb mettre (to put), the je and tu forms take an "s" (je mets, tu mets), but the il/elle/on form drops it, becoming il met.

Why does appât have a circumflex accent over the second "a"?

A circumflex in French often replaces an "s" that used to exist in Old French. The word appât originally had an "s" and shares a root with the English word "pasture" (animal food). Thinking of that hidden "s" is a great way to remember that it means "bait"!

Why does hameçon contract to become l'hameçon instead of staying le hameçon?

The word hameçon starts with a silent h (h muet). Because the h is completely silent and has no breath attached to it, the word is treated grammatically as if it starts with a vowel, forcing the definite article le to drop its "e" and contract to l'.

Why is there a cedilla (ç) in hameçon?

The cedilla (the little hook under the c) forces the letter "c" to make a soft "s" sound when it comes right before the vowels a, o, or u. Without it, the "c" before the "o" would be pronounced with a hard "k" sound.