Learn Italian: Questo letto è largo e comodo. - This bed is wide and comfortable.

Largo is a false friend—a word that looks like English but means something else. In Italian, largo always means "wide" or "broad". If you want to say a bed is "large" or "big", you would use the word grande.

Why do questo, largo, and comodo all end in the letter -o?

They are all describing letto (bed), which is a masculine singular noun. In Italian, adjectives and pointing words like questo (this) must match the gender and number of the noun they describe, so they all take the masculine singular -o ending.

Since this lesson is about comparatives, how would I say this bed is "wider" or "less comfortable"?

Italian doesn't add endings like "-er" to make comparisons. Instead, you just put più (more) or meno (less) before the adjective! "Wider" is più largo (literally "more wide"), and "less comfortable" is meno comodo.

How is comodo pronounced? Is the emphasis on the middle O?

Actually, the stress is on the very first syllable: CO-mo-do. While many Italian words place the stress on the second-to-last syllable, comodo is a very common exception to watch out for.