This is the 14346th most frequent Russian word.
открывал
"Открывал" means "opened" (past tense, masculine form).
In this sentence, 'открывал' refers to the repeated action of opening the door in the past.
Он открывал дверь каждый вечер.
He opened the door every evening.
Here, 'открывал' describes a past continuous action, indicating that the action of opening the window was in progress when another action occurred.
Когда я пришёл, он как раз открывал окно.
When I arrived, he was opening the window.
In this example, 'открывал' is used metaphorically to mean 'discovered' or 'learned,' applied to gaining new knowledge or insights.