Learn Hardcore Romanian: Andrei citește același ziar în autobuz. - Andrei reads the same newspaper on the bus.

The infinitive is a citi (“to read”). In the present indicative, the third-person singular form is built from the stem citi- plus the ending -ește. So el/ea citește = “he/she reads.” (By contrast, citesc is “I read” and citești is “you read.”)

How do you pronounce the diacritics in citește, același, and în?

Romanian has five special letters:

ș (comma S) = /ʃ/ as in English “sh”
ț (comma T) = /ts/ as in “cats”
ă = /ə/, a schwa like the ‘a’ in “about”
î (or â) = /ɨ/, a central vowel somewhat between /i/ and /u/
So:
citește ≈ “chee-TESH-teh”
același ≈ “ah-cheh-LAʃ”
în ≈ a one-syllable /ɨn/, like a quick “uhn.”

What does același mean, and why is there no article before ziar?

același means “the same” and acts as a determiner. In Romanian, when you use a demonstrative or a word like “same,” you do not add a separate article. Thus același ziar = “(the) same newspaper.” You cannot say “același ziarul” or “un același ziar”. If you wanted just “the newspaper,” you’d say ziarul, but with “same” you stick with același ziar.

Why is it același (masculine) and not aceeași? How would it change for feminine or plural nouns?

Romanian adjectives and demonstratives agree in gender and number with the noun they modify. ziar is masculine singular, so you use același. For a feminine noun like carte (“book”), you’d say aceeași carte (“the same book”). For plural you’d use aceiași (masculine) or aceleași (feminine).

Why is there no article before autobuz, and when would you say în autobuz versus în autobuzul or într-un autobuz?

în autobuz (no article) expresses a general location or habitual action “on the bus” (e.g. during his commute).
în autobuzul adds the definite enclitic -ul (“in the bus” as a specific one: e.g. the red bus you see every day).
într-un autobuz (merge of în + un) means “in a bus,” highlighting that it’s just any bus. All three are correct but carry different nuances of definiteness.

Could you use a different preposition like pe autobuz or cu autobuz here?

în autobuz = inside the bus (location).
pe autobuz is not used for location in modern standard Romanian (you say pe tramvai, but for buses it’s în).
cu autobuzul or cu autobuz means “by bus” (as a means of transport), not “while inside the bus reading.”

Why is the sentence word-order Andrei citește același ziar în autobuz, and can you omit Andrei altogether?

Romanian typically follows Subject-Verb-Object, same as English. You could drop Andrei because the verb ending -ește already shows it’s “he/she.” So Citește același ziar în autobuz is grammatically fine if context makes clear who “he” is. You could also say El citește… for emphasis, but it’s optional.