
blinken
to flash
A repeated, brief lighting up and going out of a light.
Die Warnleuchte am Armaturenbrett begann rot zu blinken.
The warning light on the dashboard began to flash red.
to flash / indicate
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to flash
A repeated, brief lighting up and going out of a light.
Die Warnleuchte am Armaturenbrett begann rot zu blinken.
The warning light on the dashboard began to flash red.

to indicate
To use a vehicle’s turn signal to show a lane change or a turn.
Du musst vor dem Abbiegen rechtzeitig blinken.
You have to indicate in good time before turning.

to gleam
To light up brightly and shine or shimmer, often through the reflection of light.
Die frisch polierten Gläser blinkten im Kerzenschein.
The freshly polished glasses gleamed in the candlelight.
The verb 'blinken' (to flash) is used only for light sources, not for the movement of the eyes. When eyes quickly close and open, German uses a different verb.
Die Sterne blinkten am Nachthimmel.
The stars flashed in the night sky.
The exact meaning of 'blinken' (to flash / indicate) depends heavily on the context. In road traffic, it refers to the turn signal. With technical devices, it is a warning or status signal. In poetic language, it describes the shimmering of surfaces.
Bitte blinke, bevor du die Spur wechselst.
Please indicate before you change lanes.
In the context of driving, 'blinken' (to indicate) is very often combined with a direction. The most common phrases are 'rechts blinken' (to indicate right) and 'links blinken' (to indicate left).
Der Fahrer vor mir hat nicht geblinkt und ist einfach abgebogen.
The driver in front of me didn’t indicate and just turned.
In the meaning of 'schimmern' (to shimmer), 'blinken' (to gleam) is often connected with a light source or a reflective place. Typical formulations are 'in der Sonne blinken' (to gleam in the sun) or 'im Licht blinken' (to gleam in the light).
Der frisch gefallene Schnee blinkte in der Morgensonne.
The freshly fallen snow gleamed in the morning sun.
to flash
Both words can describe a brief flash of light. „Blitzen“ generally suggests a single, brief flash, while „blinken“ refers to light that repeatedly comes on and goes off. Use „blitzen“ for a one-time flash and „blinken“ for a regular signal.

Die Warnleuchte blinkte mehrmals, solange die Tür offen war.
The warning light flashed repeatedly as long as the door was open.
Die Warnleuchte blitzte einmal kurz auf, als der Strom zurückkam.
The warning light flashed briefly once when the power came back on.