Questions & Answers about Я думаю про неї.
Word by word:
- Я – I (1st person singular pronoun, nominative case)
- думаю – (I) think / am thinking (1st person singular, present tense of думати – to think)
- про – about / of / regarding (preposition)
- неї – her (object form of вона – she, used after a preposition)
So the whole sentence is literally “I think about her.”