This is the 11962nd most frequent Russian word.
зафиксировать
To record, secure, or fix.
Here, "зафиксировать" is used to mean 'to record or note down' something specific in writing or electronically.
Я зафиксировал дату встречи в календаре.
I recorded the meeting date in the calendar.
This sentence uses "зафиксировать" to refer to 'capturing an image or event' using a device such as a camera.
Фотограф зафиксировал на пленке момент взрыва.
The photographer captured the moment of the explosion on film.
In this example, "зафиксировать" denotes the act of 'detecting or noting' a condition or occurrence, often in the context of observation or monitoring.