Kiel malbona ulo li estas!

English Translation

What a bad boy he is!

“Kiel malbona ulo li estas!” translates to “What a bad guy he is!” in English. Let’s break down the grammar and vocabulary:

Kiel: This word means "how" or "what a" in exclamatory sentences. It's used here to express the degree of the following quality.

malbona: This is an adjective meaning "bad." In Esperanto, adjectives usually end in "-a."

ulo: This noun means "guy" or "person." In Esperanto, most nouns end in "-o."

li: This is the pronoun for "he" or "him."

estas: This is the verb "to be" in its present tense form.

Combining these elements, “Kiel malbona ulo li estas!” uses:

Kiel to introduce an exclamation.
malbona to describe the quality (bad).
ulo as the noun being described (guy).
li to identify who is being referred to (he).
estas to link the description to "li."

So the sentence structure is employed to emphasize the badness of the person being talked about, creating an exclamatory statement “What a bad guy he is!”