a heads up

To give someone "a heads up" is to alert them to some situation or event which is likely to interest or affect them.
The metaphor relates to the need to lift up your head and eye level in order to see something significant of which a companion is already conscious.

Συνοπτική προειδοποίηση

привлечь внимание, предупредить кого-л. о ситуации или событии, которые могут (обычно: негативно) отразиться на нём.