This is the 6727th most frequent Japanese word.
パブロ
"パブロ" is a transliteration of the name "Pablo" in Japanese.
The word 'パブロ' is a personal name, specifically 'Pablo', which is a common name that can be used to refer to someone in a sentence.
パブロはスペインから来ました。
Pablo came from Spain.
The word 'パブロ' in this sentence is used as an object of the verb '知っています' (to know), indicating familiarity with the person named Pablo.
私はパブロを知っています。
I know Pablo.
Here, 'パブロ' is used as an indirect object of the verb '書きました' (wrote), showing the recipient of the letter.