der Schirm
umbrella / parasol
A fold-out object that protects against rain (umbrella) or sun (parasol).
Weil es regnete, spannte sie ihren Schirm auf.
Because it was raining, she opened her umbrella.

umbrella / shade
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umbrella / parasol
A fold-out object that protects against rain (umbrella) or sun (parasol).
Weil es regnete, spannte sie ihren Schirm auf.
Because it was raining, she opened her umbrella.

'Schirm' (umbrella / shade) is a very productive base word. Many meanings can be recognized from the compound: 'Regenschirm' (umbrella, against rain), 'Sonnenschirm' (parasol, against sun), or 'Bildschirm' (screen, for images).
Nimm einen Regenschirm mit, es soll heute regnen.
Take an umbrella with you; it's supposed to rain today.
The context reveals which 'Schirm' (umbrella / shade) is meant. Words like 'Regen' (rain) or 'aufspannen' (to open) point to an umbrella, 'Lampe' (lamp) or 'Licht' (light) to a lampshade, and 'Computer' (computer) or 'fernsehen' (to watch TV) to a screen.
Bei dem starken Wind konnte ich den Schirm kaum halten.
In the strong wind, I could hardly hold the umbrella.
In connection with an umbrella or parasol, typical verbs are used: you 'spannt' a 'Schirm' 'auf' (open an umbrella) to open it, and 'klappt' it 'zu' or 'macht' it 'zu' to close it.
Als der Regen aufhörte, klappte er seinen Schirm zu.
When the rain stopped, he closed his umbrella.
The expression 'unter dem Schirm von jemandem/etwas stehen' (to be under the patronage of someone/something) means that a person or project is protected or supported by an influential authority. The preposition 'unter' (under) is crucial here.
Die Veranstaltung steht unter dem Schirm der Bürgermeisterin.
The event is under the patronage of the mayor.
The informal expression 'jemanden/etwas auf dem Schirm haben' (to have someone/something on one's radar) means to be aware of something or to keep an eye on it. The preposition 'auf' (on) is a fixed part of the expression here.
Ich habe auf dem Schirm, dass die Frist nächste Woche endet.
I have it on my radar that the deadline ends next week.
Using 'Schirm' (screen) for a monitor or screen is informal. In more formal or technical contexts, the more precise word 'Bildschirm' (screen/monitor) is preferred.
Schau nicht so lange auf den Schirm, das ist schlecht für die Augen.
Don't look at the screen for so long; it's bad for your eyes.
protection
'der Schutz' and 'der Schirm' can both mean that someone or something is kept safe from harm. However, 'der Schutz' is the more general word. It fits safety from danger, illness, cold, or violence, and can also refer to a protective measure. 'der Schirm' is usually a concrete object, for example against rain or sun. In fixed expressions like 'unter dem Schirm von' (under the patronage of), 'Schirm' can also figuratively mean protection or supervision. In everyday language, you are more likely to say 'Schutz' when talking about safety in general, and 'Schirm' when you really mean the object.

Nimm bitte einen Schirm mit, weil es heute Nachmittag regnen soll.
Please take an umbrella with you, because it's supposed to rain this afternoon.
Beim Wandern ist guter Schutz vor Sonne und Kälte wichtig.
When hiking, good protection from sun and cold is important.