Funnier means more amusing. Much funnier, funnier than the first, gets funnier.
The y turns to i before -er, as in happier and easier, and the comparative is one word rather than more funny — two-syllable adjectives ending in y take the ending. Funny also means odd, so funnier can mean stranger, which the context has to settle.
1adjectivefunnierMore amusing.
“His second film is even funnier than the first, and I cried with laughter.”
funnier is a comparison.