glühend
glowing
So hot that it gives off light by itself. Often used for metals, coal, or lava.
Der Schmied formte das glühende Eisen mit dem Hammer.
The blacksmith shaped the glowing iron with the hammer.

glowing
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glowing
So hot that it gives off light by itself. Often used for metals, coal, or lava.
Der Schmied formte das glühende Eisen mit dem Hammer.
The blacksmith shaped the glowing iron with the hammer.

'Glühend' (glowing) is the present participle of the verb 'glühen' (to glow). It is used like a normal adjective and is declined before a noun.
Vorsicht, das Metall ist noch glühend!
Careful, the metal is still glowing!
The noun that 'glühend' (glowing/ardent/scorching) describes reveals the meaning. 'Glühendes Eisen' (glowing iron) means physical heat, a 'glühender Anhänger' (ardent supporter) means passion, and 'glühende Hitze' (scorching heat) refers to the weather.
Der Vulkan spuckte glühende Lava.
The volcano spewed glowing lava.
In the figurative meaning, 'glühend' (ardent) is often combined with people or feelings. Typical examples are 'ein glühender Anhänger' (an ardent supporter), 'eine glühende Verehrerin' (an ardent admirer), or 'glühender Hass' (burning hatred).
Er ist ein glühender Fan dieser Fußballmannschaft.
He is an ardent fan of this football team.
To describe extreme heat from the sun, 'glühend' (scorching) is often combined with words like 'Hitze' (heat) or 'Sonne' (sun). A typical phrase is 'in der glühenden Mittagssonne' (in the scorching midday sun).
Sie suchten Schutz vor der glühenden Nachmittagshitze.
They sought shelter from the scorching afternoon heat.
hot
'heiß' and 'glühend' can both describe very strong heat or strong feelings. 'heiß' is the general word for high temperature and fits many everyday situations. 'glühend' is stronger and more vivid. Literally, it fits things that glow from heat, such as coal or metal, or extreme sun. Figuratively, 'glühend' describes very strong enthusiasm or passion. You can remember it this way: everything that is 'glühend' is very hot, but not everything that is 'heiß' is glowing.

Die glühende Kohle lag noch lange im Grill.
The glowing coal stayed in the grill for a long time.
Meine Schwester hat auf der Reise einen heißen Kaffee verschüttet.
My sister spilled a hot coffee during the trip.