Eu sunt aici.

In Romanian, the verb ending already shows the subject, so you can often omit eu unless you want to emphasize or clarify who is doing the action.

• Eu sunt aici and Sunt aici both mean "I am here."
• Use eu when you really want to stress "I" (not someone else).

Sunt is the first-person singular present tense of the irregular verb a fi ("to be"). It corresponds to English "I am."
The main present-tense forms are:

• eu sunt (I am)
• tu ești (you are)
• el/ea este (he/she is)
  …and so on.

Pronounce sunt as [sunt]:

• s like in "snake"
• u like the "oo" in "put" (short)
• n and t as in English
  Keep it fairly short and crisp.

Aici means "here," indicating a location near the speaker. The opposite is acolo, meaning "there" (further away). You can use them with este or other verbs to point places:

• Aici este casa = "Here is the house"
• Casa este acolo = "The house is there"

Yes. Romanian word order is quite flexible.

• Eu sunt aici = neutral statement ("I am here")
• Aici sunt eu = emphasizes "here" ("It is here that I am!")
• Sunt eu aici? (with rising intonation) = conveys surprise or a question ("Am I here?!")

Place nu before the verb:

• Eu nu sunt aici = "I am not here."
  You can still omit the pronoun: Nu sunt aici.