Breakdown of Я наконец понял то, что учитель объяснил на лекции.
я
I
учитель
the teacher
объяснить
to explain
на
in
Questions & Answers about Я наконец понял то, что учитель объяснил на лекции.
Why is it понял and not понимаю or понимал?
Понял is the past tense of the perfective verb понять.
Here it means something like I finally understood / I finally got. The speaker is talking about a completed moment of understanding in the past.
Compare:
- Я понимаю = I understand / I am understanding now
- Я понимал = I understood / I used to understand / I was understanding (imperfective, focusing on process or ongoing state)
- Я понял = I understood / I realized / I got it (perfective, focusing on the result)
Because наконец means finally, Russian naturally uses понял here: the moment of understanding was achieved.
What does наконец mean here, and where can it go in the sentence?
Наконец means finally / at last.
In this sentence, it emphasizes that the speaker understood something only after some delay or difficulty:
- Я наконец понял... = I finally understood...
Its position is fairly flexible, though some positions sound more natural than others:
- Я наконец понял то, что учитель объяснил на лекции.
- Наконец я понял то, что учитель объяснил на лекции.
Both are possible. Putting наконец right before понял is very natural because it highlights the verb: finally understood.