Learn Romanian: Sunt aici.

In Romanian, you do not always need to say the subject pronoun like eu (I). Because the verb sunt already tells us who is doing the action, dropping the pronoun is perfectly normal and usually sounds more natural.

Wait, I thought sunt meant "they are". Can it mean both "I am" and "they are"?

Yes! The verb a fi (to be) is special because sunt is the exact same form for both eu (I am) and ei/ele (they are). The context of the conversation almost always makes it clear who you mean. If you really need to avoid confusion, you can just include the pronoun: Eu sunt aici (I am here) or Ei sunt aici (They are here).

Is aici related to the word acolo?

Exactly! They are a pair of adverbs used to describe location. Aici means "here" (close to the speaker), while acolo means "there" (further away). You will typically see both of them placed right after the verb.