Present and past perfect tenses

The present perfect tense is formed using the auxiliary verb have / has in the present tense and the main verb in the third form: have / has + done or have/has + waited
Present Perfect Tense

Present Perfect Tense is the present perfect tense in English. It denotes an action that has completed at the present time. Indicates that the action expressed by the Present Perfect time has completed by the present moment or in the present time period:
The shopping center has just opened. – Торговый центр только что открылся.

Shows that the action began in the past, but continues in the present, is still relevant in the present:
He has written this article for seven days. – Она пишет статью семь дней (Она начала писать семь дней назад и продолжает работать над ней сейчас)

Shows that the action took place in the past, it is not known and it does not matter exactly when, but its result is visible in the present:
He knows her name. They have already met. – Он знает её имя. Они уже встречались.

Indicates that the action expressed by the Past Perfect time happened before another action or a certain moment in the past:
We came to the office, but the administrator had already gone away – Мы пришли в офис, а администратор уже ушёл
Past Perfect Tense

Indicates that the action started in the past and continued until a certain point in the past:
His article was interesting. He had written it since Friday. – Его статья была интересной. Он писал её с пятницы.

Indicates that the action happened in the past and became the cause, led to the fact that another action happened in the past:
My brother felt hungry. He had not eaten since yesterday. – Мой брат был голоден. Он не ел со вчерашнего дня.