Learn Spanish (Latin America): El señor habla japonés.

The word habla comes from the regular verb hablar (to speak). Since we are talking about el señor (a "he"), we drop the "-ar" ending and add "-a". If you wanted to say "I speak," you would use hablo, and for "you speak," you would use hablas.

Why is japonés written with a lowercase "j"?

In Spanish, the names of languages and nationalities (like japonés, inglés, or español) are not capitalized unless they are the very first word of a sentence.

Why is there an accent mark on the "e" in japonés?

The accent mark shows you exactly where to put the stress when speaking. It tells you to emphasize the final syllable (ja-po-NES). Without that mark, the default Spanish pronunciation rules would make you stress the second-to-last syllable (ja-PO-nes).

Does señor always mean "gentleman"?

It can mean "gentleman," "sir," or "Mr." depending on how it is used. When used by itself like in this sentence, it translates to "the gentleman" or "the man." If it were followed by a last name, like el señor Pérez, it would translate to "Mr. Pérez".