This is the 2440th most frequent Russian word.
позвонил
"Called" (past tense, masculine form).
In this sentence, "позвонил" is in the past tense and indicates the action of making a phone call to someone.
Вчера я позвонил маме.
Yesterday, I called my mother.
Here, "позвонил" is again in the past tense, but it describes someone else initiating the phone call.
Позвонил врач и сказал, что мои анализы готовы.
The doctor called and said that my tests are ready.
In this sentence, "позвонил бы" is used in a polite and hypothetical manner to request action.